STATE NORMAL SCHOOL LOS ANGELES, CALIFORNIA UNIVERSITY of CALIFORNIA AT LOS ANGELES LIBRARY THE LIBRARY OF HOME ECONOMICS A COMPLETE HOME-STUDY COURSE THE PRACTICAL APPLICATION OF THE MOST RECENT ADVANCES PREPARED BY TEACHERS OF RECOGNIZED AUTHORITY FOR HOME MAKERS, MOTHERS, TEACHERS, PHYSICIANS, NURSES, DIETITIANS, PROFESSIONAL HOUSE MANAGERS, AND ALL INTERESTED IN HOME, HEALTH, ECONOMY AND CHILDREN TWELVE VOLUMES NEARLY THREE THOUSAND PAGES, ONE THOUSAND ILLUSTRATIONS TESTED BY USE IN CORRESPONDENCE INSTRUCTION REVISED AND SUPPLEMENTED CHICAGO AMERICAN SCHOOL OF HOME ECONOMICS 1911 2, -5 COPYRIGHT, 1907 BY HOMK ECONOMICS ASSOCIATION Entered at Stationers' Hall, London All Rights Reserved DEDICATED TO MRS. HELEN C, KIMBERLY WHOSE INTEREST IN THE EDUCATION OF THE HOME-MAKER AND WHOSE ENCOURAGEMENT AND ASSISTANCE HAVE HELPED TO MAKE POSSIBLE THE LIBRARY OF HOME ECONOMICS AUTHORS ISABEL BEVIER, Ph. M. Professor cf Household Science, University of Illinois. Author U. S. Government Bulletins. "Development of the Home Economics Movement in America," etc. ALICE PELOUBET NORTON, M. A. Assistant Professor of Home Economics, School of Education, Uni- ver itv of Chicago ; Dnectjrot the Chautauqua School of Domestic Science. S. MARIA ELLIOTT Instructor in Home Economics, Simmons College; Formerly Instruc tor School. of Housekeeping, Boston. *.NNA BARROWS Director Chautauqua School of Cookery ; Lecturer Teachers' Columbia University, nnd Simmons College ; formerly Editor can Kitchen Magazine;" Author " Home Science Cook Book." College. "Ameri Chicago; Visiting Physician Presb>terian Hospital, Chicago ; Author of '' Disea ALFRED CLEVELAND COTTON, A. M., M. D. Professor Diseases of Children, Rush Medical College, University of Visiting Physiciar ases of Children." BERTHA M. TERRILL, A. B. Professor in Home Economics in Hartforu ocnool of Pedagogy; Author of U. S. Government Bulletins. KATE HEINTZ WATSON Formerly Instructor in Domestic Economy, Lewis Institute; Lecturer Uni.ersity ot Ch.cago. MARION FOSTER WASHBURNE Editor "The Mothers' Magazine;" Lecturer Chicago Froebel Asso- ciation ; Author " Everyday Essays," " Family Secrets," etc. MARGARET E. DODD Graduate Massachusetts Institute of Technology ; Teacher of Science, Woodward Institute. AMY ELIZABETH POPE With the Panama Canal Commission ; Formerly Instructor in Practical and Theoretical Nursing, Training School lor Nurses, Presbyterian Hospital, New York City. MAURICE LE BOSQUET, S. B. Director American School of Home Economics ; Member American Public Health Association and American Chemical Society. CONTRIBUTORS AND EDITORS ELLEN II. RICHARDS Author " Cost of Food," " Cost of Living," " Cost of Shelter," " Food Materials and Their Adulteration," etc., etc.; Chairman Lake Placid Conference on Home Economics. MARY HINMAN ABEL Author of U. S. Government Bulletins, "Practical Sanitary and Econ- omic Cooking," " Safe Food," etc. THOMAS D. WOOD, M. D. Professor of Physical Education, Columbia University. H. M. LUFKIN, M. D. Professor of Physical Diagnosis and Clinical Medicine University oi Minnesota. OTTO FOLIN, Ph. D. Special Investigator. McLean Hospital, Waverly, Mass. T. MITCHELL PRUDDEN, M. D., LL. D. Author "Dust and Its Dangers " "The Story of the Bacteria," "Drink ing Water and Ice buppl es ; " etc. FRANK CHOUTEAU BROWN Architect, Boston. Mass.: Author cf "The Five Orders of Architec ture," " Letters and Lettering." MRS. MELVIL DEWEY Secretary Lake Placid Conference on Home Economics. HELEN LOUISE JOHNSON Professor of Home Economics, James Millikan University. Decatur. FRANK W. ALLIN, M. D. Instructor Rush Medical College, University of Chicago MANAGING EDITOR MAURICE LE BOSQUET, S. B. Director American School of Home Economics. BOARD OF TRUSTEES OF THE AMERICAN SCHOOL OF HOME ECONOMICS MRS. ARTHUR COURTENAY NEVILLE President of the Board. MISS MARIA PARLOA Founder of the first Cooking Fchool in Boston; Au hor of ''Home Economics," "Young Housekeeper," U. S. Government bulletins, eic. MRS. MARY HINMAN ABEL Co-worker in thn " New England Kitchen," and the "Rumford Food Laboratory;" Author of U. S. Government Bulletins. " Practical Sanitary and Economic Cooking," etc. MISS ALICE RAVENHILL Special Commissioner sent by the British Government to report on the Schools of Home Economics in the United States, Fellow of the Royal Sanitary Institute, London. MRS. ELLEN M. HENROTIN Honorary President General Federation of Woman's Clubs. MRS. FREDERIC W. SCHOFF President National Congress of Mothers. MRS. LINDA HULL LARNED Past President National Household Economics Association ; Author of " Hostess of To-day." MRS. WALTER McNAB MILLER Chairman of the Pure Food Committee of the General Federation of Woman's Clubs. MRS. J. A. KIMBERLY Vice President of National Household Economics Association. MRS. JOHN HOODLESS Government Superintend Ontario: Founder Ontar: the M..cDona!d Institute. Government Superintendent of Domestic Science for the province of * Ontario; Founder Ontario Normal School of Domestic Science, now FOREWORD HE Library of Home Economics is the result of some years' experience in teaching by corre- spondence what may be termed the ' ' New Pro- fession of Home Making," and what Mrs. Ellen H. Richards has called the fourth " R " in education Right Living. ^1 It is realized that the business of housekeeping has not kept pace with the tremendous advancement in other lines of human endeavor, that the wonderful discoveries in science and developments in the arts only slowly and partially have been applied to the problems of personal health and home life. fl With the object of giving home-makers and mothers, everywhere, some of the benefits of the teaching now offered in a number of colleges under the terms, do- mestic science and home economics, the correspondence courses of the American School of Home Economics were planned. Special lesson papers or text books were necessary, for ordinary text books are not adapted to correspondence instruction. From some years of experi- ence in correspondence teaching in other lines, it was known that the lesson books, to be successful, must be simple, concise, non-technical, and above all sufficiently interesting and of immediate practical value to hold the attention of the student throughout the course. fl The aim has been, not to teach science nor to teach theory, as sucn, but rather the best scientific practice with sufficient theory to show the reason "why" for such practice; in a word, to give as much real help and prac- tical information as possible. (J After much planning and consultation, well known teachers were invited to prepare the lesson books from the standpoint of the average woman, and later these same teachers have given or supervised the correspond- ence instruction. The whole course is so planned that each series of lessons fits into and supplements the others, making one logical whole, without duplication. C| From the expressed appreciation of nearly two thou- sand students, the results sought would seem to have been attained. The scientific accuracy and scholarly tone of the books is attested by their use as text books in many prominent schools and colleges. Although prepared primarily for the woman in the home, as the books natur- ally embody the teaching experience of their authors they have been found especially valuable to teachers and to those preparing themselves for various positions. l| The Library contains the complete series of iessons s including test questions, which the active members of the School answer in writing and send in, as a written recitation, for the correction and comment of the teachers. This correspondence work has given the text a most rig- orous and effective test for clearness of statement and adaptability. In republishing the lessons for the Library such revisions have been made as seemed necessary to clear up all obscure points and to rectify original de- ficiencies. (J In addition, much supplementary material of interest has been added by the authors, based on their experience in correspondence instruction. A number of special ar- ticles of importance are also included. ^ At the back of each volume will be found a program or outline for supplemental study, making virtually an ex- tension of each series of lessons. These are arranged primarily for classes taking up courses with the School by the group plan, but they should prove of equal value to the individual student and be very suggestive to teachers. The reference books mentioned and the small amount of apparatus required when experiments are sug- gested are loaned to members of the School when not available locally. ^ In place of prefaces to the volumes, reproductions are given of the introductory letters of the instructors which are sent to students when each new subject is begun. *lThe Library is published to give the members of the School their course of study in permanent form, with indexes for ready reference, and in binding worthy of the contents. It will also serve as a reading course for asso- ciate members of the School and will be available as a general reference work, making the public acquainted with the character and merit of the correspondence courses of the American School of Home Economics. y It is in hope that it may serve as an inspiration and an authoritative guide for inexperienced home-makers; that it may open up a new world of interest to the expen- enced home-maker and give added meaning and impor- tance to familiar tasks; that it may, in some measure, increase health and happiness, that the Library of Home Economics is offered. VOLUMES I THE HOUSE: ITS PLAN, DECORATION AND CARS II HOUSEHOLD BACTERIOLOGY III HOUSEHOLD HYGIENE IV CHEMISTRY OF THE HOUSEHOLD V PRINCIPLES OF COOKERY VI FOOD AND DIETETICS VII HOUSEHOLD MANAGEMENT \ T III PERSONAL HYGIENE IX' HOME CARE OF THE SICK X TEXTILES AND CLOTHING XI STUDY OF CHILD LIFE 'XII CARE OF CHILDREN LOUIS PASTEUR. FATHER OF BACTERIOLOGY Household Bacteriology BY S. MARIA ELLIOTT INSTRUCTOR IN HOUSEHOLD ECONOMICS SIMMONS COLLEGE, BOSTON CHICAGO AMERICAN SCHOOL OF HOME ECONOMICS 1911 SSOO4 COPYRIGHT, ige4, BY AMERICAN SCHOOL OF HOUSEHOLD ECONOMICS COPYRIGHT, 1906, IQIO, BY HOME ECONOMICS ASSOCIATION Entered at Stationers Hall, London All Rights Reserved QT154, CONTENTS LETTER TO STUDENTS . . . v DUST ...,.. i DUST-GARDENS ...... 7 DUST PLANTS . . . * . . 15 BACTERIA ....... 16 MOLDS . . . . . . . 33 YEASTS . . . . . . . 3Q WORK OF BACTERIA . . . . . 47 BUTTER MAKING . . . , 57 CHEESED. . " . . . . . . 58 VINEGAR . . . . . . .60 HARMFUL DUST PLANTS ..... 63 PRESERVING FOOD . . . . . .69 DISEASE GERMS . . . . . 75 RESISTANCE OF THE BODY . . . . .86 SANITATION ..... 96 HISTORY OF BACTERIOLOGY . . . .109 SUMMARY . . . . .113 EXTRACTS FROM THE INSTRUCTOR'S NOTE BOOK . 11; SAFEGUARDS OF THE BODY AGAINST DISEASE, BY T. MITCHELL PRUDDEN . . . .127 BIBLIOGRAPHY . . . . . .153 SUPPLEMENTAL STUDY OUTLINES . . . . 157 INDEX i63 AMERICAN SCHOOkOF HOME ECONOMICS CHICAGO January 1, 1907. My dear Madams In beginning our work in Household Bacteriology together I should like to make a few suggestions as to aims and methods of study. The aims to be reached in the study of any science are at leaat two a knowledge of its un- derlying principles and as thorough an application of those principles as is possible. For the principles you will consult the lesson booklets. From them, too, you will gat suggested applications, but the subject will not become a. part of yourself until you recognize new applica- tions nany times a day. It is said that no person KNOWS a foreign language until he can think in that language. In a similar way you will want to think these facts into your life and work. Suggestions for study have already been given to you. I hope that you nay be able to try all of the experiments suggested; at least make a "dust garden" as described. If you can get no suitable dish, a regular Petri dish may be obtained through the School for 30 cents and a tube of prepared "nutrient gelatine ".for 20 cents. The dish may be returned. Also, I hope that you will read some of the books recommended in the bibliography. The facts of bacteriology underlie so firmly all our daily living that there is no need to go far afield for illustrations. But a thorough knowledge of the science can be gained only through laboratory methods and with a microscope . There- fore , I hope you may be able sometime to supple- ment this study by microscopic work. Perhaps through the aid or some doctor or other scientist you may be able now to get a peep into this world of the unseen. If these les'sons point out dangers of which you were before unconscious, they also suggest ways of escape from those dangers. You will gain some knowledge of the causes of waste and disease If this leads you to efforts for the prevention and removal of such causes, the result will be those healthful conditions which make the most effectual safeguard against the attacks of the few micro-organisms that are our foes. I hope the relations between hygiene and some of the daily tasks of housekeeping will gain a deeper significance in your mind: and this ele- mentary study may result not only in pleasure and profit to you, but also, through you, in better conditions of healthful living for others. Sincerely yours. Instructor T H I HTH 1AT ten billions of dollars are expended annually in the United States for food, clothing, and shelter with greater knowledge and efficiency, better satisfaction could be obtained and one billion dollars saved for higher things. AT half a million lives are cut short and five million people are made ill by "preventable" diseases every year with universal knowledge of hygiene and sanitation nearly all deaths and illness from such causes could be prevented. "THAT six hundred thousand infants under two years end their 1 little span of life yearly, while millions of children fail to reach their best physical development because their mothers and fathers understand not how to care for them in the light of science with more knowledge at least half the number of babies could be saved and the physical standard raised immeasurably. AT thousands of homes are wrecked, tens of thousands of lives are ruined, and hundreds of thousands are made unhappy because the home-keepers of our country have no training in the greatest of all professions, the "profession of home- making and motherhood" only through such education can present domestic difficulties be solved and the modern home contribute all that it should to happiness and well being. T all must live in some sort of a home that everyone" finds his chief happiness there that character is developed there that no great advance, spiritual or material, is possible which does not begin with the home that the home-makers of America have the making of the nation. '"THAT on the breadth and strength of the base depends the 1 height of a pinnacle on the home foundation we rear the pinnacle of all that is good in state or individual. American School of Home Economics HOUSEHOLD BACTERIOLOGY 2-300 4- MOST persons now know that mankind is greatly troubled by the work of certain minute agents variously termed germs, bacteria, micro-organ- isms. Few, however, realize the good that these forms do, or understand them and their place in the world. It is the purpose of the following pages to show the relations, both good and evil, that bacteria and other micro-organisms bear to the household. DUST Most housewives look upon dust as an undesirable prevalence thing that they are constantly seeking to be rid of. If dust is seen on the piano or on the table each thinks she will be considered a slack housekeeper. Perhaps some are not troubled by the presence of .dust that does not show. Such fight the enemy vigorously where vis- ible, but relax effort where or when he is invisible. The temptation comes to hide the tell-tale dust by shutting out light. Few persons there are who have not at some time HOUSEHOLD BACTERIOLOGY. Dust-proof Boom or House Necessity of Dust exclaimed, "Where does all the dust come from?" If a house be thoroughly cleaned from cellar floor to attic ridge, tightly closed for months or years, when re- opened dust will be found in great quantities. This is true even in the country, where perhaps a single house, removed from the highway, stands sur- rounded by grass and trees. The "housekeeping" of ships includes dusting. The officers' quarters of the government ships are dusted regularly, although land may not be seen for months at a time. Scientists have tried to get a dust-proof room or house in which to carry on their experiments. This has required attention to location and site, that there should be no jar from traffic or vibration from winds ; a careful preparation of the surrounding soil ; numer- ous walls separated from each other and made largely of glass, carefully joined and hermetically sealed. The air admitted must be freed from its dust ; all clothes ordinarily worn by the experimenter must be ex- changed for garments especially prepared and cared for, before he enters this to-be-dustless room. Even then all surfaces need to be slightly moist, that any stray speck of dust which has escaped all these guards may be caught and held. Such conditions as these can never be secured in ordinary life, so that dust will probably be present with us always. Indeed, it is probable that were all dust exterminated, life also would become extinct, for life in its most efficient forms needs light, and Tyndall DUST. 3 proved by delicate experiments that when all dust was removed from the track of a beam of light, there was darkness. So before the command, "Let there be light," the dust condition of light must have been pres- ent. Balloonists find that as they ascend higher the color of the sky deepens. At a distance of some miles the sky is nearly black, there is so little dust to scatter the rays of light. If the stellar spaces are dustless, they must be black, and therefore colorless. The mois- ture of the air collects about the dust-particles, giving us clouds, and with them all the glories of sunrise and sunset. Fogs, too, are considered to be masses of "water-dust," and ships far out at sea have had their sails colored by this dust while sailing through banks of fog. Astronomers find meteoric dust in the atmosphere. Meteoric When this falls on the snow and ice fields of the Arctic regions it is readily recognized. The eruption of Kra- katoa proved that volcanic dust is disseminated world- wide. An old writer has said : "The sun discovers atomes though they be invisible by candle light, and makes them dance naked in his beams." Thus dust, just common every-day dust, is a very source important and complex substance, which promises much of interest in its study. Therefore, again we ask where does it come from and of what is it made? When a March wind blows over a sandy road or a November gale sweeps through city streets, it is evi- dent that a large part of the dust found in the house 4 HOUSEHOLD BACTERIOLOGY. comes through open doors and windows. Few win- dows and doors are so tightly fitted that fine dust will not sift in round their casings, ingredients Until electricity is made the common source of heat of Dust - and light, there will be much dust from coal and wood, both before and after they are burned. These sources are too evident to need more than a mention. It is from the wear and tear of the house itself, its finish and furnishings, from our own bodies and the clothing that covers them, that the larger amount of dust comes. From these we have bits of wood, stone, cotton, hair, dead cells from all animal bodies a mass of mineral, animal, and vegetable matter of very complex compo- sition. Since time began, everything in this old world has thus been wearing away more or less slowly, adding bit by bit to similar accumulations, until what we know as soil has been built up pure mineral soil made from the debris of the rocks ; organic soil or loam from the addition to this mineral soil of vegetable and ani- mal debris. The same processes are continually going on all about us. The dictionaries recognize this process when they tell us that dust is "Earth or other matter in fine dry particles so attenuated that they can be raised and car- ried by the wind." M of m Dust Winds then are the responsible agents for much of the dust in our houses, but wind is simply air in mo- tion. We cannot walk across the floor, make a bed, rock comfortably in a chair, or dance a jig without DUST. 5 making some wind currents. If dust is present in this current, it will be stirred up to settle back, where it was before, or to be blown to some other place. The more dust or the stronger the wind, the surer it is that the dust will be carried along with the current. But why should the housewife spend so much energy why Keer and time in trying to keep her house free from dust? Dust All the dust elements we have seen so far are not likely to do her much harm. The ashes or other mineral dust may scratch the polished table or the brass ornaments and silverware, but not so long as it lies quiet. It is the moving grain of sand, not the still one, that scratches. The other ingredients, bits of dead animal or vegetable matter, may be disagreeable to think of, but they are of the same stuff as ourselves, our clothes, our furniture. If this dead matter were all there is to dust, no one would ever have heard of the science of bacteriology. Many of the dailv occurrences in the home give Familiar Experience* rise to questions which may be readily answered if we will but turn our kitchens into laboratories and try some simple experiments. Perhaps you forgot to change the water in a vase of flowers and it stayed there a week. How did it smell when you poured it out ? How did the stems that had been in the dirty water feel? Possibly when you left home for a week's visit last summer, you knew the ice was all gone from the refrig- erator, but you forgot to empty the pan underneath. 6 HOUSEHOLD BACTERIOLOGY. What did you find on your return ? A slimy film ovei the surface of the water, did you not? Such experiences may be familiar to all. A few years ago these changes were thought to be due to the oxygen of the air, which in some way, under certain conditions, made some things sour, some bitter, and others putrid. ^ n ^ e ^ a y s ^ our g Tan d r nothers much of the bread was made with leaven like that used in Bible times a mixture of flour and water exposed to the air and whatever the air contained. This, was called "barm." Such bread is still common in some parts of our country, and known as "salt-rising bread," and the barm when made with milk is called "milk emptins." In the old days a portion of the leavened mass was kept to start the next batch of bread. Occa- sionally this was forgotten or it spoiled, then the housewife borrowed from her neighbor, as when the fire on the hearth was out, a coal was borrowed. Sometimes now the yeast raised sponge becomes slight- ly sour before it is ready for baking. Why ? Apple or other sauces containing sugar ferment or sour and the housewife scalds them. This may make them as palatable as when freshly stewed. Yet they often turn sour again and, after a while, scalding or even boiling does not remove the sharp or sting- ing effect upon the tongue. MOW The moist bread in the jar is found specked with mold ; some August morning the sprinkled clothes DUST GARDENS. 7 in the laundry basket are mildewed; the "best room," seldom used and darkened by drawn shades and tight- ly closed blinds, becomes musty. What do all these things mean, or have they any re- lation to each other? We will now see if we can answer these questions. Experiments with Dust Experiment I. Mix a little yeast with some sweet- ened water and let it stand in a warm place where the temperature is from 70 to 75 Fahr. Put a few table- spoonfuls of beef broth or molasses water into a cup or bottle and leave it uncovered in the kitchen where it will be warm. Watch carefully what happens. Be- fore long bubbles show on the surface of the sweetened water ; perhaps you may see bubbles rising in the broth. If left long enough the sweet liquid will be sour and the good broth smell bad. You say the one has fer- mented, the other is putrid. What has made the change? You did not add anything to the mixture; you only kept it warm and uncovered. DUST GARDENS. Experiment II. From any dealer in laboratory sup- The Garden plies or through the doctor or druggist get a Petri dish or plate. This is simply two round glass dishes, one- quarter to one-half inch in depth, one just large enough to fit over the other as a cover. See Fig. i. This ex- periment can be made without the Petri dish, although not so conveniently, as follows : Take a clear glass sauce dish or a finger bowl. Fig. 2. Cover with a piece of smooth, thin glass clear 8 HOUSEHOLD BACTERIOLOGY. enough to see through readily and large enough to entirely and ' tightly cover the dish. After washing well, place both together in a pan in a cool oven and gradually raise the temperature until it is hot enough to bake bread or to yellow a piece of white paper in half a minute. Let them bake for an hour or more. Then open the oven and place the pan where the dish may cool slowly. When cold take out, without removing the covering plate, and put round both dish and plate a strong rubber band, or tie them together with a string. This we will call our garden-plot. But a garden is of little use without something growing in it, and for this soil is required. FIG. 1. PETRI DISH FOR PLATE CULTURES. Soil for the For the soil take the following recipe : Chop finely one-quarter pound of lean, juicy beef. Mix this with one cup of warm water. Heat in double boiler, stir- ring often until water in water pan has boiled fifteen min-ites. Remove inner dish, place directly over the fire and allow broth to boil ten or fifteen minutes. Clear by straining through two or more thicknesses of DUST GARDENS. 9 flannel wet in cold water. Squeeze the meat carefully to get out all its juices but not much fat. The meat is acid, therefore, add from one-eighth to one-quarter teaspoonful of bi-carbonate of soda. Replace the water lost through evaporation. Moisten three heaping tablespoonfuls of finely di- vided gelatine in a very little cold water and add to FIG. 2. SHALLOW BOWL COVERED WITH SHEET OF GLASS. the boiling hot broth. When the gelatine is dis- solved, strain through hot flannel. Put three or four tablespoonfuls of the broth into each of several small bottles. Plug the mouth of each with a close wad of cotton wool or tie over each a thick mat. of the same. For three successive days place the bottles on a piece of folded cloth in a pan of cold water and boil them fifteen minutes. Gelatine melts at quite a low temperature, so if the dust garden is prepared in summer it may not re- main solid. If kept in a very warm place in the room it may melt at any time. A better substance to use for the jelly is agar, which remains solid at blood heat, 98.5 Fahr. This may be found in some cities at the druggists', or at the dealers in chemical or bac- teriological supplies. It solidifies suddenly, if its temper- ture drops below a certain point, and as it is rather Planting the Garden 10 HOUSEHOLD BACTERIOLOGY. difficult to prepare, the gelatine is more favorable for the amateur's use.* In our garden we want only certain kinds of plants, and we want to know just where they come from, we, FIG. 3. COLONIES OF DUST-PLANTS, GROWN ON GELATINE. (After Conn.f) therefore, bake the dish and boil the jelly until sure that nothing in either is alive. When ready to plant the garden, put the bottle of jellied beef juice into a dish of cold water. Heat this until the jelly is melted and then cool slightly. *For the careful, accurate preparation of such soil, consult "Laboratory Work in Bacteriology," Frederick G. Novy, or any other manual of laboratory practice in Bacteriology. A Petri dish may be obtained from the School for 3OC and a bottle of agar ready for use for 24C (in stamps) sent postpaid. tThe "Story of Germ Life," H. W. Conn; D. Appleton & Co., Publishers. DUST GARDENS. n Remove the elastic from the dish. When the tube or bottle of jelly is cool enough to be held in the hand, remove the cotton , wool plug^ or stopper, carefully raise the cover of the dish on one side, just enough to insert the mouth of the bottle. Pour the melted jelly into the dish, cover, and gently turn with a circular motion until the jelly is spread evenly over the bottom of the dish. Replace the elastic and let the jelly harden. The garden is now ready for planting. To do this, all that is necessary is to remove the cover and leave the dish open for from twenty to thirty minutes. If opened in a very dusty place, expose only ten min- utes. Do not go near or meddle in any way. At the end of the time replace the cover and the elastic band. Let the dish remain in a warm room not above 70 F, and watch carefully for whatever happens. In the course of thirty-six to forty-eight hours or longer, minute light-colored specks will show on the surface of the jelly. These will be seen to grow larger, to become of different colors pink, yellow, orange, green, blue, possibly a deep red. Some spots will be shiny, smooth, and round; oth- ers branched like mosses or seaweeds ; others with white rims and dark centers, showing a pile like velvet, and, when seen through the sides of the dish, they may suggest minute pins with ball heads. Fig. 3. All of these forms may not show themselves, but in most cases there will be seen the shiny, smooth spots, 12 HOUSEHOLD BACTERIOLOGY. and the hairy or velvety ones. Look at the garden through a magnifying glass, if possible ; watch even- change; write down an accurate and full account as to time, appearance, conditions of temperature, light, etc. Then change the conditions. Put the dust- garden into the refrigerator, shut it into a box, etc. See how the colonies are affected by each new condi- tion or by any two combined. If a compound miscroscope can be used, touch the point of a needle to one of the spots and place the speck of matter taken up on a clean glass slide. Put on a drop of cool boiled water, and over this a cover glass; examine carefully .for shape and motion; draw what is seen. In this way examine the differ- ent colonies to see if the forms in all are of the same shape. Putrefaction L e t: the dust garden grow for a week or more, then gently raise the cover, smelling of the contents, and as this is done, if the growth is sufficiently far ad- vanced, there will be sensible proof that dust-plants may cause putrefaction. The next time you are tempted to leave a piece of meat exposed, remember the dust-garden, and cover the meat with a cloth to keep out dust. Figures 4 and 5 are photographs of such dust-gar- dens after more than two weeks' growth. The prin- cipal colonies of molds are marked o, and those marked b are colonies of bacteria. In Fig. 5 the row of colonies marked 6' shows well how thickly they FIG. 4. PHOTOGRAPH OP A DUST GARDEN AFTER TWO WEEKS GROWTH. Colonies of Mould Marked a ; Colonies of Bacteria not Marked. DUST GARDENS. 13 sometimes crowd together. Probably these were all attached to some tiny fibre of wood or cloth. The soil or "nutrient gelatine" in our experiments Kindg had beef juice in it; you will ask if any other soil would do. The gardener knows that his pinks will grow better in one place and his ferns in another be- cause each requires or likes, we may say, a particular kind of food which that soil contains. In the laboratory numerous soils or nutrient media are used milk, potato, beer, blood-serum, etc. A moment's thought will show that all the food substances which we like best are subject to changes which in general we designate as "spoiling." Some grow bitter, some sour, some odorous, some rancid. In a few cases this result is due to processes brought about by mere chemical changes that is, without the intervention of any living agent or ferment; but in most cases where food spoils, it is due to the growth on or in the substance itself of the little plants, which have been carried to it through ordinary dust. The milk in the pantry is found to be sour. When it was secreted by the milk gland in the cow's body it of UI M was sweet and pure. It passed down into the milk- duct in its passage outward, and here perhaps it met a few of the dust-plants which had passed into the mouth of the duct from the outside. Hundreds, no doubt, fell into the pail from the dusty air of the stall the cow's hairy coat, the milkman's clothes, or hands, or hair, even from the pail itself, for all are more 14 HOUSEHOLD BACTERIOLOGY. or less dusty. Among these hundreds of forms are some that like the sugar of the milk as food. While feeding upon this, they change a part of it into acid- lactic acid. When this acid reaches a certain amount, it coagulates the casein of the milk. Production The cleaner the milk, the fewer of these lactic acid producing plants will be present and the longer the milk will keep sweet. Cold retards their growth. Milk should then be cooled as quickly as possible after being drawn from the cow, and should be kept in a cold place at all times. Milk is a most favorable culture ground for bac- teria because it has some of all classes of food ele- ments, being what is known as a perfect food. Its opaqueness hides much of the solid dirt which not only seeds it with bacteria but adds certain soluble matters. Too often the dirty character of the milk is known only by sight of the actual dirt at the bottom of the empty glass. The possibilities in the way of clean milk, which means safe milk, were forcibly illustrated by exhibits from some American "model dairies" at the Paris Ex- position in 1904. Milk and cream in a perfectly fresh condition were shown after a journey of ten days; the only treatment being extreme cleanliness in milking, sta- ble, receptacle, etc., and cold. A glass of ordinary, un- clean milk contains millions of bacteria, which al- though harmless to a vigorous adult are the cause, di- rect or indirect, of the death of thousands of young children annually. FIG. 5. A DUST GARDEN. (a) Colonies of Mould. (b) Colonies of Bacteria, (b') Colonies of Bacteria on a Thread. DUST PLANTS. 15 DUST PLANTS We have seen from the dust-garden that dust does contain living plants which, when they find food in a moist, warm place, will grow and multiply. They were not seen when they settled out of the dust on the jelly, and not until they had reproduced Fig. 6. (a) One Colony of Bacilli or Rod-Shaped Bacteria "Dust Garden." Highly Magnified. (b) Eight Bacteria from the Colony, Magnified Much More. (After Prudden.) themselves many times, so that a "colony" was formed, were we able to see that Anything had been planted in the dust garden. But each colony or spot shows where a single plant dropped on the gelatine; the spot becomes visible only after it contains thousands of in- dividuals, which are kept close together by the gelatine. 16 HOUSEHOLD BACTERIOLOGY. Names of All of these dust-plants have to be studied under Dust Plants the 'microscope and are therefore called micro-organ- isms. Microbe a name given by Louis Pasteur which from its derivation would include all, has come gradually to be applied to one class, the bac- teria. Still a third word, germ, which really means the beginning, or that first living cell which produces a more complex form, is becoming restricted to the micro-organisms that cause disease, as the germ of tuberculosis, the germ of typhoid fever, etc. All these names may apply to micro- scopic animal forms as well. Strict- ly speaking, all dust-plants are germs, all are microbes, all are micro-organ^ isms. The "garden" will show two kinds of plants and sometimes a third, although this is not so com- mon in house dust. We will now see what these three kinds of plants are > two of which we may expect tO filld in a11 h USeS at an . V timC ' Forma. (b> Baeiin The third, wild yeast, would verv or Rod-shaped Mil 8 ' or J sp i f ft n 'kely ke caught if we planted our forms. d us t garden under the apple trees in summer time. BACTERIA Let us find out first what the plants are like which make the smooth, glossy, shiny colonies, whether round or radiate. These are the bacteria, and each colony BACTERIA. 17 has come from the reproduction of one parent a bacterium. Fig. 6. Under the microscope these bacteria show three principal shapes. Fig. 7. One like a short, round stick or rod, is called a bacillus and bacilli for the plural. Fig. /b. Another is ball-shaped, called coccus or cocci for the plufal (the third c sounding like s). Fig. 73. A third form which resembles one turn or more of a screw is called a spirillum or spirilla for the plural. Fig. 70. These typical forms may shade into each other. The bacilli may be long or short, with pointed/ blunt, or square cut ends. They may be so short and plump as to closely .re- semble a coccus. Fig. 8. The spi- ral forms may curve very little or have decided and numerous twists. Fig- 9- Bacteriologists do not always agree as to which class a newly found indi- vidual should belong, and to the housewife it makes no difference. The bacteria are so simple in structure and so dim"- structure Bacteria cult to study that there is little to describe. Each consists of a single cell, so far as is known. This seems to have a denser portion on the outside, which forms a cell wall and may be cellulose as in the higher plants. This simple cell of protoplasm or "foundation stuff" Excretions 18 HOUSEHOLD BACTERIOLOGY. is endowed with all the characteristics of living matter anywhere. All living things whether plant or animal take food in some way. All, too, having taken food, change it over into their own substance and give out FIG. 9. DIFFERENT FORMS OF SPIRILLA. some 'of the results of these changes as waste prod- ucts in the form of gases, liquids, or solids. Bacteria are no exception to this universal rule. Their products are either gases or liquids and these, dissolved in blood or other liquids, bring about vari- ous changes, the results of which may be either de- sirable or undesirable, according to the nature of the bacterium, the amount of the excretion, or other con- ditions under which the changes are wrought. The processes of bacterial growth in the human body and in food substances are similar. "DUST GARDEN" SHOWING ABUNDANT GROWTH OF MOLDS Made by a Member of the A. 8. H. E. BACTERIA. The excretions of the bacteria in milk, fish, etc,, may produce changes which, very apparently, ren- der them unfit for food, or the changes may not be apparent. If food containing these excretions be eaten, or if the bacteria grow in the body itself, the excretions may bring about abnormal conditions more or less severe, but all may be called disease. Like the mag- gots in cheese or the clothes moth larva, the bacteria live surrounded by their food supply and they have only to take, digest, and absorb it as need- ed. Like these animal forms, they feed upon com- plex organized food which has been previously pre- pared by other plants or animals. In this they differ from most plants which must manufacture their food out of the mineral and other inorganic substances in air, water, or soil. However, some species can do this although they have not the green coloring mat- ter or chlorophyll cells which in the higher plants are the food factories. Because of this power of living on inorganic sub- stances, which no known animal possesses, the sci- entists have decided that these micro-organisms must be called plants rather than animals. Bacteria have no leaves, roots, stems, or any or- A BACILLUS DIVIDING INTO TWO GENERATIONS. HOUSEHOLD BACTERIOLOGY. Food of Bacteria Reproduction of Bacteria gans like higher plants. They are simply transpar- ent bits of jelly-like protoplasm. Bacteria in general like the same kinds of food that man likes, although they do not require the variety in diet which to civilized man seems necessary. Some flourish best in meat juices, others in milk, some in starchy foods, others in su- gary solutions, while still others enjoy best Fig. 11. Different Forms of Bacilli. the fats. (a) Simple, detaened forms. (b) Chains of united bacilli. They algo show> j ike man, a surprising faculty of adaptation. If unable to get their favorite food, many will grow on whatever is at hand. Any organic substance which is not absolutely dry may become food for some species of dust-plants. Dust-plants will not leave the moist surfaces upon which they fall, but where such surfaces become dry, then the plants are ready to be blown into the air by winds or carried along on anything which touches them. Ordinarily dust particles are probably never so dry that the bacteria or other micro-organisms clinging to them are killed. All bacteria reproduce by division of the parent into halves, which process is called fission. Fig. 10. Sometimes these daughter cells remain attached even after they themselves have divided into two. A BACTERIA. 11 chain of cells results so that what looks under the microscope like one individual may be three or more generations. Fig. n. The ball forms divide in the same way along a di- ameter. Some, however, divide in more than one di- FIG.- 12. REPRODUCTION OF COCCI BY FISSION. (a) Division into two.. (c) Division into four. (b) Chains of cocci. (d) A sheet of four cocci. rection, so that the colony of daughter cells may touch at one side only, like closely strung beads, or on two sides, making a sheet or film of cells, or they may become piled upon each other like a cube of marbles. Fig. 12. 22 HOUSEHOLD BACTERIOLOGY. The spiral forms also may remain in one colony or break up into single cells after division. Sometimes they unite their bodies by a gelatinous film to form a slime over the sur- face of whatever FIG. is. ZOOGLOEA OR THE they are growing FILM-FORMING BACTERIA. ' upon, as seen on the walls of the waste pipe of the refrigerator or on the surface of the water in the pan. This is known as a zoogloea form. Fig. 13. Rapidity The rapidity with which they reproduce depends largely upon the food supply, the warmth and moist- ure that is, whether the conditions of life and growth are favorable. In this prolific reproduction lies their great power for harm or benefit to the world. In some species, under favorable conditions, a new generation is born oftener than every half hour. If this rate were continued for a day, one bacterium might become ancestor of over sixteen million de- scendants. Some interested observer has calculated that in two days the billions thus born would fill a pint measure and weigh a pound, while in another twenty-four hours their weight would equal eight thousand tons. These numbers, however, are of no practical im- BACTERIA. 23 portance, for long before such a population was reached the food supply would be gone or the parent forms would be killed by their own excretions. Here, as in the animal world, if the wastes of living accu- mulate, death results. Yet wherever conditions of moisture, warmth, and food remain favorable they will multiply with almost infinite rapidity. Botanically the bacteria belong to the fungi, and Bacteria because they reproduce by fission or breaking into as Funp two, they are called Schizomycetes or Fission Fungi. A string of sausages, often seen hanging in the win- dows of a market, is a fair representation, except in size, of a chain colony of bacteria. Take a piece of white rubber tubing, ten to twelve inches long and from one-half to one inch in diam- eter. Tie it tightly at one end with waxed thread. Fill this about three-quarters full of water and tie the second end so that no water may escape. From thread to thread will represent very well a bacillus. Divide this in the middle by a rubber band and two generations are represented or a chain colony of two individuals. The same method may be continued to show the future reproduction processes. Their minute size would seem to indicate insig- size of Bacteria. nificance, but they make up in energy, in the work done, and in numbers, for all that is lacking in size. Not one is ever visible to the naked eye, while some can be seen only with great difficulty by the skilled observer and under the most powerful microscope. They are so small that little idea of their size can 24 HOUSEHOLD BACTERIOLOGY. be obtained by actual measurement, only by compari- son. Fig. 14 represents the largest bacterium known magnified six hundred diameters. One twenty-five thousandth of an inch is not an uncommon length for a bacterium. Yet, small as they are, they are heavier than air, and therefore settle out of it when it is still. It is estimated that in the space occupied by a grain of sugar there might be packed six hundred mil- lions and each bacterium be com- fortable. Compared with the bac- Fi g . Ti. Bacillus teria which may lodge there, the (a a*a ga bf rlu individ- wrinkles in the skin of our hands ( C u and d) TWO indi- are like ditches six or eight feet v V K 8 'into eaC baive d s: deep. No wonder that it is diffi- cult to dislodge them by any ordi- nary washing. The surgeon has to resort to a strong soap, vigorous brushing, and the use of numerous bacterial poisons in addition to the ordinary washing, before he is sure that these valleys are not rich in the tiny plants that might bring suffering or death to his patient. to R oxygen Most of the bacteria require oxygen to breathe, as we do, but some can live without air. Some will ac- commodate themselves to any condition. Preferring much or little oxygen, they will, however, grow under the opposite condition, if they must. BACTERIA. 25 Of course, the disease germs which grow in the in- terior of our bodies flourish best under conditions of darkness and lessened air supply. Out-of-door life, then, is a preventive measure, and next to this is a Disease and FIG. 15. SUNSHINE AS A DISINFECTANT. (After Lefar.) Under the letters of black paper there was growth; In the remainder of the plate the sunlight killed the bacteria. generous supply of sunlight and fresh air inside our houses. Experiments have shown that the disease germs HOUSEHOLD BACTERIOLOGY. Effect of Sunlight Power of Movement live much longer when grown in a cellar than when cultivated in the light rooms of a house. All disease germs, so far as known, are killed by direct sunlight. This was proved some years ago by planting a Petri dish with typhoid fever germs. Half of the dish was covered with black paper, while the uncovered half was exposed to direct sunlight. On the sunlighted half no growth appeared, while the other half showed many colonies. A similar ex- periment is illustrated by Fig. 15. In this experiment the letters of the name "Ty- phus" were cut out of black paper and placed on the under side of the cover of a Petri dish which had been planted with bacteria. The dish was exposed to sunlight for an hour and a half and then left in a dark room for twenty-four hours. When the paper letters were removed, the space covered by them was found thickly studded with the minute colonies of bacteria. The rest of the plate showed no appearance of bacterial life. Some bacteria, like most of the higher plants, re- main stationary, having no power of motion, while others move by slow or jerky, worm-like contrac- tions. Still others are moved about by whip-like ex- tensions of their bodies, called flagella or cilia. Some have only one whip at one end of the body, others one or a cluster at each end, while others have them reaching out from all parts. Fig. 16. Some bacteriologists place all the forms which have BACTERIA. 27 without flagella in one species Bacillus, and all flagella in another species Bacterium. When for any reason there comes a period of hard times in the life history of the bacteria, such as cold, dryness, or lack of food, some bacteria have the a FIG. 16. BACTERIA WITH FLAGELLA. (a) A flagellum at one end. (b) A flagellum at each end. (c, d. and e) Tufts of flagella In different positions. (After Conn.) power of contracting their bodies into smaller space, possibly drawing it all into ons end or from the mid- dle into each end. Fig. 17. This is called the spore stage. These spores can weather great extremes of famine or cold or resist the action of strong chem- icals. Some can be frozen, others boiled and still re- tain life. When good times return in the form of Spores HOUSEHOLD BACTERIOLOGY. Resistance of Spores Dust Plants in the Refrigerator moisture, warmth, or more food, the resting, resist- ant spore starts into growth again and continues its life as before. The species that do not form spores are much more easily killed. Those that form spores readily, being difficult to kill, are more likely to cause dis- ease or destruction of property. Fortunately for us, most of the disease or "pathogenic" germs do not. form spores readily, if at all. It is these spores that make necessary the repeated "scalding" by which the housewife tries to save the food which she finds spoil- ing. The lowest temperature known will not kill some bacteria, while some varieties in the spore state will resist the temperature of boiling water. Indeed the heating sometimes seems to favor their changing into the active state. Dust readily finds access to the ice box or the refrig- erator, even if the ice is thoroughly cleaned before it is put in. The dust-plants will grow on any bits of food carelessly dropped and by their gaseous products may taint the meat, milk, and other foods. The escape pipe of a refrigerator needs to be often and carefully cleaned throughout its entire length, else it will be covered with a slimy mass of bacterial erowth. Many of the bacteria found here are the germs of putrefac- tion. This pipe may be cleaned with a swab of cloth or sponge tightly wrapped around a long stick, rat- tan or whalebone, with a small, long-handled brush, BACTERIA. 29 or if the pipe is too difficult of access for these methods, a boiling hot solution of washing soda may be poured down once a week, or when the ice box is empty. The pan under the refrigerator should be scrubbed carefully with hot soapsuds or scalded with the wash- FIG. 17. VARIOUS SPORE BEARING BACTERIA, (a) Spores Escaping from Ruptured End. (After Conn.) ing soda, that no slime may appear. The escape pipe, too, should be opened to the air and in a place where the air will be pure. The housewife who allows her refrigerator pipe to empty directly into a hole in the cellar floor, un- derneath which is a slimy mass of muddy filth, need not be surprised that milk and butter do not "keep well." 30 HOUSEHOLD BACTERIOLOGY. Boiling The greatest argument in favor of boiling clothes in the laundry is based on the bacteriological reason. Body clothes, bedding, towels and handkerchiefs may all become soiled with discharges of the mucous mem- branes of the body or from some wound or pus formation. In most of these discharges there is sure to be bacteria. Soap has a slight disinfecting power, but the boiling is far more efficacious. Scalding or the pouring of boiling water over the clothes is not sufficient for disinfection, for only the top surface is subjected to the high degree of heat necessary to kill the germs. Soap or other alkali, boiling, fresh air, and sunshine are a sanitary quartet whose work results in sterilization that is, in death to the germs. Natural The natural home of the bacteria is the soil. Here Home of Bacteria they, are most numerous because here they have their greatest field of work laid out for them, which is to change any dead vegetable and animal matter that may be present into inorganic substances which can do no harm to life. When winds blow over the soil they raise the dry dust particles laden with bacteria into the air ; rain washes millions of them from the air and soil into the brooks and rivers ; therefore, all surface waters are seeded with bacteria. From the soil they may be directly brought into the house on shoes, or clothes, or hands ; indirectly through dusty air. The cleaning of shoes on a mat, brush, or scraper BACTERIA. outside the front door is a habit to which all chil- dren should be trained. Adults should think what it means to bring street filth into the dry, warm house. If all coats, dresses, etc., worn on the street could be brushed out of doors still another fruitful source of dangerous dust would be avoided. House air is found to contain thousands of bacteria, where out-of- door air may have only hundreds, because moist sur- faces catch and hold them. Sunlight and large amounts of fresh air tend to kill them. The house has less fresh air, less sunshine, and it is filled more or less with dry, rough furnishings, which add to the dust and all tend to hinder its removal and to lessen the chances of disinfection. In the laboratory bacteria are studied in many ways. Under the microscope is noted their shape and size; what kind, and the rapidity of motion, if any; how they tend to arrange themselves upon division ; whether spores are formed or. not. From plate and other cultures can be seen the shape and color of the colony ; whether they grow best on the surface, in much air, or below the surface where air is excluded; whether the temperature of the room is more favorable than that of the incubator, which is much higher and represents more nearly the conditions inside of our bodies. Some of the bacteria secrete an acid which lique- fies the gelatine on which they may be growing. This acidity can be detected by litmus paper. Some pro- duce a gas when grown in a sugary solution, others laboratory Study Secretions 32 HOUSEHOLD BACTERIOLOGY. cause putrefaction. Each of these differences means much to the trained observer, for from such result;? has been and must be gathered our knowledge of their probable behavior outside of the laboratory, importance In the bacteriological laboratory has been found out facts which in the commercial life of the world mean millions of dollars ; there, too, have been started experiments which have led to incalculable saving of human suffering and life, through sanitation, pre- ventive medicine, and surgery. Here we see how the little things of life have con- founded the mighty and how ''the science of the infinitely small," by which some one has defined bac- teriology, "has become the infinitely important." DUST PLANTS. -S3 Another micro-organism which is seldom absent from house dust, either as the plant cell itself or its spore, is mold. This in our dust garden formed the :olonies with dark centers and a velvety pile. Molds Growth of Mold FIG. 18. A GROWTH OF MOLD. Mycelium, Hyphae and Spore-cases. (After Jorgensen.) consist of vegetative portions which grow out in long threads, and these by budding and branching unite to form a network over the substance they are using as food. Fig. 18. From this network or mycelium grow out cells called Jiyhae set apart for special wprk that of bearing the reproductive portion the heads or stalked clubs. Inside these heads or from their outer surface 34 HOUSEHOLD BACTERIOLOGY. FIG. 19. MOLDS SHOWING A MYCELIUM BRANCH, (m.) (a) With ripe spores (s). (b) A spore-bearing stalk with spores just forming. (c) Spores have fallen. (After Jorgensen.) MOLDS. 35 grow the spores which are to reproduce the species. Figs. 19 and 20. Each head produces thousands of dust-like spores. Fig. 21. This is the common method of reproduction in the molds, although some, like the bacteria be- low them in the scale of nature, break the parent cell into segments, while others send off buds like yeast. These buds form di- rectly the second generation. When the invisible spore falls upon a moist, warm surface, it immediately begins to grow by sending out the mycelium branches, which will then proceed as before to develop more spore-bearing cells. Sometimes these mycelium cells pene- trate into the food substance, very much r IG. 20. like the roots of the higher plants. One of the effects of mold growth is seen in the soft- ening of cellulose in fruits, vegetables, etc. This makes their decomposition by the bacteria more speedy and thorough. Out-of-doors this action is of great use in the economy of Nature, but inside our houses the pres- ence and growth of molds should be guarded against in every way. In general, molds will grow with less moisture than bacteria, and -some of them flourish in the light. They increase rapidly after rainstorms and are much less affected than the bacteria by winds. They need or- ganized food, as we well know from the places where we find them growing bread, meat, leather, sugary liquids, or even in vinegar. Hold Spores Work of Molds 36 HOUSEHOLD BACTERIOLOGY. In general, they form fewer desirable products than do the bacteria, although this may be consid- ered a matter cf taste. Those who like Limburger and Brie cheese ; the Chinese "soy," which is made from a kind of bean on which mold has grown ; the Japanese "sake" or rice wine, which has been fer- mented by molds these persons certainly would claim that molds were as valuable in the production Disease from Molds FIG. 21. DIFFERENT STAGES IN THE DEVELOPMENT OF MOLD. (a, b, c and d) Growth of the spore-cases. (d') The spore-cases open. (e) Spores. (After Jorgensen,) of flavor as the bacteria are in butter and ordinary cheese. Just what their action is upon digestion is not defi- nitely understood. It is thought that many of them cause a lax condition in the bowels, possibly diar- rhcea. They are found to cause various diseased condi- tions of the skin Ringworm, Thrush, and Moth. The moth patches, often called Liver spots, because believed to be due to an inactive liver, are found to be caused by mold spores which have gained access to MOLDS. 37 the body tissues through some break in the skin. Fairly strong acetic acid 40 per cent is one of the best remedies for moth. They sometimes penetrate quite deeply into the tis- sues, causing irritation, inflammation, or sores very difficult to heal because there can be no healing until the plant is killed. Food fully penetrated by mold growth would bet- ter be destroyed. When the growth occurs only on the surface, as on jelly, olives, pickles, etc., the mat of cells protects the food beneath and most of it is un- harmed. Such foods, however, are often softened by the products of mold and bacterial growth, when no sign of mold appears on the fruit itself. If eaten, various intestinal disorders are liable to occur. Moist cloth furnishes favorable soil for mold when warm and not open to fresh air. The folded gar- ments laid away gather moisture ; dust containing mold spores is usually present on them, and in time, soon or late, the garments grow musty even if there be no visible mold. Mustiness is the proof of mold, and mold the proof of dampness and dust. We call the mold growing on the cloth mildew, but called by either name it is the same dust-plant. The plant must be killed to stop its growth. If it has grown only on the surface of the fibre, the stain may sometimes be removed without serious injury. If it is of long growth or has penetrated the fibre, a hole will result, because of the weakened or actually destroyed fibre. So far as the healthful house is concerned, there 38 HOUSEHOLD BACTERIOLOGY. need be no separation in the mind between molds and bacteria, because the occurrence and conditions of growth of both are practically alike. So far as is known, there are no molds that cause such serious and fatal diseases as some of those caused by bacteria. Because molds are lighter than the bacteria, it takes much longer for them to settle. The air, then, is likely to contain molds even where it has been quiet so long that the bacteria have all settled. This gives the housewife another reason for the economy of keeping the air of her kitchen, pantries, or any place where food is prepared or "stored, as free from dust and as dry as possible. Moldy In old houses it is sometimes impossible to keep food in certain closets or cupboards. The woodwork or plaster and therefore the air is so charged with mold spores that one damp day or the presence of warm, moist food alone will cause them to spring into growth. Such places should be often white- washed and painted or disinfected. The spores of molds are often very beautiful in color when seen in mass, and under the microscope they show exquisite forms and delicate ornament. These factors, as well as the substances upon which the mold grows, are used as means of distinguishing species. The botany of molds is to many as interesting a study as that of the higher plants. Only a micro- scope can bring out the beauties of this class of dust- plants, which from the standpoint of economy and health the housewife can view with disfavor second YEASTS. 39 only to that she bears for some of the bacteria. So many more of the bacteria are friends rather than foes that it may be more just to place mold as her chief enemy. The third variety of plants found in dust is yeast, size and Structure These are not usually so numerous as either the bac- of Yeaat teria or the molds, although about apple trees in the country wild yeasts are common. Like a bacterium, the yeast plant is a single microscopic cell of pro- toplasm enclosed by the cell wall. It is round or oval in shape and often one two-thousandth of an inch in diameter. Fig. 22. It is therefore quite a giant com- pared with the smallest bacterium. If a drop of tepid water in which bread yeast has been dissolved be carefully watched under the micro- scope, the changes shown in Figs. 23 and 24 may be seen. One cell will be seen to swell a little at one part. This bud or daughter cell will bulge out more and more from the parent and may even produce one or more generations from itself before it breaks away. This "budding" is the method of reproduction common to yeast plants of which there are many varieties. Some species, however, reproduce by spores very Spores much like the molds. Such yeast cells will be seen to divide within the cell wall into two or four rounded bodies which in growing soon rupture the parent cell and escape. Fig. 25. Each of these liberated spores forms a new plant which may produce buds. Requirements for Growth 40 HOUSEHOLD BACTERIOLOGY. Thus the generations are continued and the individuals multiplied. Yeast requires food, oxygen, warmth, and moisture. Sugary substances are especially liked by the yeast which is used to make bread. This is a specially cul- tivated form of brewer's yeast. Yeast directly from TYPICAL FOEMS AND APPEARANCE OF BREWERS- YEAST. (After Sedgwick and Wilson.) Products of Growth the breweries is often used for breadmaking. It is while feeding upon these sugary solutions that the tiny plants bring about the chemical changes by which alcohol and the gas, carbon dioxide, are pro- duced. The gas puffs up the dough and makes pos- YEASTS. 41 sible the raised bread, or the- "election cake" like that of our grandmother's time ; it also produces the "froth" and '"sparkle" of the "home-made spruce beer" as well as that of the large breweries. Yeast plants grow best from 70 F. to 90 F. They FIG. 23. A YEAST GARDEN. do not work well under 70 F. and are killed when in a moist state by the temperature of 130-! 50 F. No wonder the bread will not rise when the cook pours boiling or even hot water on the cake of yeast! Dead plants cannot work any more than dead animals. No Favorable Temperature Cold *nd Yeasts 42 HOUSEHOLD BACTERIOLOGY. working by the yeast means no possible raising of the dough by the gas. Sometimes the dried yeast cake has been carelessly prepared in this respect and the yeast plants are nearly all dead. The yeast plants can endure cold better than heat. FIG. 24. YEAST PLANTS IN VARIOUS STAGES OF BUDDING OR REPRODUCTION". (After Sedgwick and Wilson.) Experiment with Yeasts It hinders their work but does not quickly kill them. To show the favorable or unfavorable tempera- ture for the growth of yeast plants, take one-half cup each of boiling, lukewarm and ice-cold water. Add to each one tablespoonful of molasses and one- YEASTS. 43 sixteenth of a cake of compressed yeast. Put each portion into a clear glass bottle or tumbler and place all three in a warm place, about 75 or 80 F., for an hour or two. Watch carefully for the first sign of bubbles which show that gas is forming. Note in which glass the larger amount of gas is found. OC FIG. 26. YEAST GENERATING CARBON DIOXIDE. (a) Tube filled with molasses and water. (b) Carbon dioxide collecting In top of tube. Fill a test tube or thin, clear glass vial with a mixture of molasses and tepid water. Add a little yeast and invert the vial in a dish which also con- tains molasses and water. Fasten the vial so that it will remain standing, closed, in the dish for a day or more. Fig. 26, a and b. 44 HOUSEHOLD BACTERIOLOGY. The Gas Produced Compressed Yeast The gas will be formed, replacing the water in the vial. If a burning match is held in the mouth of the tube as it is removed from the' water, the flame will be extinguished. This indicates that the vial con- tains the gas carbon dioxide ; or a teaspoonful of clear lime water may be poured into the vial and shaken about in it. The carbon dioxide present will turn the lime water milky from the insoluble car- bonate of lime (calcium) formed. Compressed yeast is sim- ply a mass of yeast plants mixed with some form of starch and pressed into cakes. A two-cent cake is said to contain over half a billion yeast plants. As these cakes are made .or a special purpose they should contain only one species of yeast. They do, however, contain bacteria and if the dough is allowed to rise too long or at too high a temperature they grow and produce an acid which makes the bread sour; so that sour bread results from the growth of bacteria and not from the yeast. When pure yeast is used and all conditions of cleanliness are carefully looked after no sour bread results. A dusty kitchen or unclean utensils may increase the danger from bac- terial growth. If the bread be made with milk, this should be scalded to kill the bacteria always present. As we have seen, milk is rich' in dust-plants, especially FIG. 25. A YEAST CELL CON- TAINING FOUR SPORES. YEASTS. 45 bacteria, and the dirtier the barn, the cows, the pails, or the clothes and hands of the milker, the more bac- teria the milk contains. The baking of bread should kill both the bacteria and yeasts, as well as molds, if any are there. But it will not do this unless continued for a long time, because the inside of the loaf will not be raised to a temperature sufficiently high. The moisture in the in- terior prevents a temperature much higher than 212 and it may remain far be- low this. In the laboratory bread has been made from the yeast plants found alive in the center of a slack-baked loaf. The bread should re- main in the oven until well Fig. 27. Bacteria Found in the done, then when removed "Eyes- of Potatoes. it should be cooled as rap- idly as possible, that all growth of yeast or bacteria may be stopped. The custom of some housewives of wrapping the hot loaf in thick cloth that the steam may soften the crust is entirely wrong from a bacteriological stand- point. During the baking the alcohol and carbon dioxide are both driven off. Coarse breads, those containing much bran espe- coarse cially, need thorough baking, because on the outside of Meals the grains are often certain bacteria, the spores of which are very resistant to even high heat. 46 HOUSEHOLD BACTERIOLOGY. Some of these are found in large numbers in the soil which clings to underground vegetables, especially in the "eyes" of potatoes. No wonder a vegetable brush is necessary to clean away these clinging arms! Fig. 27. TEST QUESTIONS The following questions constitute the "written reci- tation" which the regular members of the A. S. H. E. answer in writing and send in for the correction and comment of the instructor. They are intended to emphasize and fix in the memory the most important points in the lesson. HOUSEHOLD BACTERIOLOGY PART I. Read Carefully. Place your name and address on the first sheet of the test. Use a light grade of paper, write on om. side of the sheet only, and leave space between answers. Use your own words, so that your instructor may know that you understand the subject. Read the lesson book a num- ber of times before attempting to answer the questions. Answer every question fully. 1. What are bacteria? Describe them. 2. What other microscopic forms are found in dust and what are favorable conditions for the growth of these dust-plants ? 3. Where are bacteria most numerous and what is their chief work in the world ? 4. In what ways are bacteria helpful to man and in what way do they injure him or his pos- sessions ? 5. Why should food eaten raw or unskinned be thoroughly cleaned ? 6. What sanitary end is attained by cooking food? 7. Why are oranges and bananas safer fruits than grapes or peaches bought from a street ven- der? 8. How can scalding apple or other sauce prevent its spoiling, and why scald it more than once? HOUSEHOLD BACTERIOLOGY. 9. What common diseases in man are attributed to molds ? 10. What is mildew, and under what conditions in the house would it be likely to appear? 11. Are molds ever helpful to man? 12. From the health standpoint, what clothes are most likely to need boiling ? 13. Why should milk receptacles be thoroughly- scalded or sunned? 14. When a can of blueberries ferments or "spoils," what does it mean ? 15. Why are bacteria considered to be plants? 1 6. How do bacteria reproduce themselves and what food do they prefer? 17. What is the typical mode of reproduction in yeast? In mold? 1 8. What is the chief work of the yeast plant? 19. Give a report of your dust-garden experiment. 20. What do you consider the most important ways in which you have applied the knowledge gained from this lesson? 21. Are there parts of this lesson that are not clear? Have you some questions? Note. After completing the test sign your full name. HOUSEHOLD BACTERIOLOGY PART II CELLS OF CLOVER TUBERCULE, SHOWING BACTERIA HIGHLY MAGNIFIED HOUSEHOLD BACTERIOLOGY PART II. WORK OF BACTERIA When bacterial life first appeared upon the earth may never be known, but that it existed thousands of years before man made its acquaintance is surely true. Indeed, it was within the last quarter of the nine- teenth century that the knowledge of bacteria became of value or was reduced to a science. The problems of bacteriology are now being solved very rapidly. What future generations may add, who can tell ? Although bacteriology is the youngest of all the sciences, it occupies a very important place among them because of its intimate connection with disease, with sanitation or the prevention of disease ; with successful agriculture, and with the manufacture of many products. In the eyes of the law every person is considered tr B efni innocent until proved guilty. It may be well for us Bacten * to look at the beneficent role which bacteria play in the world, that we may the more justly consider their harmful work. We can hardly believe that the most numerous forms of life were intended to work only harm to man. HOUSEHOLD BACTERIOLOGY Bacteria as Scavengers Fig. 28. Bacteria which Help IE Plant Food. in Soil Making As soon as an organism begins to live it begins to die ; that is, certain cells or parts of cells die and are perhaps cast off from the rest that the whole may not be injured. Animals and plants die and become dan- gerous to the welfare of other animal life, especial- ly to man. The wastes of life, of his own life even, are man's greatest menace. Here come to his aid these microscopic scavengers, the bacteria. No doubt the molds assist in the process but the balance of the work is done by the bacteria pres- ent in such infinite numbers everywhere on the earth where organic matter exists. Through their agency all dead animal and vegetable substances that is, all or- ganic matter are changed in- to inorganic matter, into the chemical compounds or ele- ments out of which they were originally constructed, and which are harmless or helpful to the life of the world. A tree falls in the woods; an elephant or a bird dies in the jungle ; just then and there the millions of bacteria in the soil and the air are ready to seize upon the dead bodies, and in time all the animal and vege- Fig. 29. Bacteria Found in Soil and on the Roots of Clover, Peas and Other Leguminous Plants. WORK OF BACTERIA 49 tables tissues are changed into gases which dissipate in- to the air or reunite into compounds that form a part of the soil. These then become once more food for plant life, and this, in turn, for the sus- tenance of animals. Bacteria are the agents of decay by which all or- ganic materials are re- turned to the soil or the air. Thereby life is not only made possible, but also is sustained. What the conditions would be were these invisible agents to cease their beneficent work of scavenging can be scarcely imagined. Life as we know it on this earth could not exist were these dust-plants not present. All animal life is de- pendent directly or indirectly upon the vegetable kingdom for sustenance. Man takes both animal and vegetable food, but he is not able to manufacture this food out of the inorganic elements. Plants use for their food gases, water, and various salts usually dissolved in the water. In sunlight the FIG. 30. A VARIETY OF PEA. soil with the nitrifying bac- Grown proper terta. Grown under the same conditions without the bacteria. 50 HOUSEHOLD BACTERIOLOGY green leaves through their chlorophyl cells are able to take most of their carbon from the carbon dioxide of the air. Some oxygen is also taken from the air, but most of it is absorbed by the rootlets from the ground air, the water in the soil, or from organic com- pounds in solution in the water. Hydrogen is ob- tained from water and other compounds containing hydrogen and is taken in through the rootlets. Nitrogen No plants can take their nitrogen directly from the * ot Direct air. Although this gas with oxygen comprises the major part of the atmosphere in which all vegetation is bathed, it is not taken in through the leaves as the carbon dioxide is. A government bulletin says : "Ever since anything has been known in regard to plant nutrition and the necessary part that various gases and minerals play in the successful growing of crops, scientific men have realized the great importance of conserving the world's store of nitrogen and have made every effort either to husband or to increase all available sources of supply. In the early days, when it was first realized that nitrogen was so essential to plant life in fact, was at the very foundation of agriculture no particular alarm was felt. Botanists had demonstrated that plants obtained their carbon from the carbon dioxide of the air, and since this gas is present in so much less quan- tity than nitrogen it was believed that by no possible means could the most essential of plant foods be ex- hausted. However, when it was shown that plants WORK OF BACTERIA were unable to use free atmospheric nitrogen and must obtain it directly from the soil in a highly or- ganized form, the importance of the problem increased greatly, and the gravest consequences were predicted by those familiar with the rapidity with which this valuable element was being wasted." Farmers' Bulle- tin No.' 214, Beneficial Bacteria for Leguminous Crops. Nitrogen in combination available for plant food is wasted in many ways. Food and other organic wastes, as sewage, are burned or run into the sea instead of being returned to the earth, which is the natural place of disposal. There are natural sources of stored nitrogen in saltpeter beds and guano deposits, but these are rapidly disappearing. Even if they were sufficient in quantity they are not everywhere present and therefore must be expensive. Their aid would not be available for all. The bacteria are more generally present and ready to work. Although unknown and therefore uncred- ited, they have been working during all the ages since vegetation appeared, not only by their general agency in producing fertility of the soil through the products of decomposition, but also in certain plants through their ability to take from the air its free nitrogen. From the earliest days of agriculture it has been recognized that all plants belonging to the leguminosae have a decidedly beneficial effect upon the soil. Pliny wrote: "The bean ranks first among the legumes. Waste of ftitrogen HOUSEHOLD BACTERIOLOGY Nitrogen Traps Enrich the Soil Inoculating the Soil It fertilizes the ground in which it has been sown as well as any manure." The lupine and vetch are also mentioned in ancient writings as enriching the soil and supplying the place of fertilizers. On the roots of these leguminous plants, clovers, alfalfas, peas, beans, etc., are seen little nodules which have been found to be filled with bacteria. Fig. 29. If these "nitrogen traps" are absent or are removed the plants are less vigorous. Fig. 30 shows the com- parative size of two plants of a variety of pea; (a) grown on soil containing the proper kind of bacteria ; (b) grown in the same conditions and soil, but with- out the bacteria. The nitrogen is stored up in the knots, swellings, or nodules on the roots. Not only do these nitrifying bacteria thus feed the plants which carry them, but also when the plants de- cay they enrich the soil in which the plants grow. Soils "run out," as the farmers say, that is, there is not plant food enough to sustain luxuriant vegetable life. Here is a place for the legumes to supply with their tiny balls of bacteria the nitrogen which has been with- drawn. In some way, not understood, the clover or similar plant in company with the bacteria stores up nitrogen from the air, which is finally returned to the soil when the decomposition bacteria have accom- plished their work, thus making the soil richer in nitrogen. When the proper kind of nitrifying bacteria are not present, the scientist comes to the aid of the farmer WORK OF BACTERIA 53 and supplies him with artificially grown bacteria with which he may inoculate the soil or seed. If the soil is favorable otherwise, the crop is greatly increased and in time the soil made more profitable for other crops. The wise farmer does not plant potatoes or corn in the same piece of ground two years in succession, unless he adds large quantities of fertilizer or plant food. He rotates his crops because different species of plants take from the soil different kinds or amounts of food. Even if these two fields of work scavenging and aid in agriculture were all in which we make use of bacteria, their claim of helpfulness would be over- whelmingly proved ; but other results of decomposition processes are valuable in the arts and in the commerce of the world. By the action of bacteria upon the whitish juice of certain plants fermentation processes are set up which result in the blue indigo so important in dyeing indus- tries. Our grandmothers would have been surprised indeed had they understood that their solid bluing was once a white liquid. Bacteria, too, make possible the retting of the flax, whereby the fibres are separated from the stalk to be finally woven into the beautiful "pictures in white" we call table damask. They bear their part in the preparation of sponges and in many processes of tanning and tobacco curing. Rotation of Crops 54 HOUSEHOLD BACTERIOLOGY In these "maceration industries" advantage is taken of Nature's methods of decomposition and what she did for countless ages before man studied her "ways and means" he still lets her do for his own and the world's commercial benefit. Her bacterial agents are as ready to work on the large scale of his planning as on the small scale of the stems of mignonette left^ too long without fresh water in a vase on our tables. Yet these are not all. Not only do they act directly and indirectly in furnishing food to plants, which afterward become food or fuel to ani- mals and man, and prove a source of wealth to man in his industries, but they also greatly increase the variety and the palatability of his food. Milk as we know it always contains bacteria and is an excellent culture material for their growth. Such a universal condition suggests some important results to be attained. Most housewives know that while cream may be sour it is not so sharply acid as the, milk from which it was taken. The addition of a little salt or sugar and spices may counteract this acidity and the result be a most delicious sauce. The large amount of fat in Fig. 31. A Bacterium Which Makes Milk Sour. BUTTER MAKING 55 the cream is not a favorable food for the lactic acid bacteria. Fig. 31. BTTTTEH MAKING Butter is usually made from sour or "ripened" cream and this ripening is the work of bacteria. The Butter bacteria which cause the ripening are of different species, which grow best at different times and under different conditions. As the re- sult of their growth are pro- duced many different odors or flavors in the cream and the butter. Those that make the most desirable flavor, aroma or taste flourish best in May or Fi ^ hie f G i4 June in this part of our country. an \er dor . tresh trom the priv, vault, from the garbage boi Irom the i ever scarlet It.er. diprilheni and ether infectious diseases The, have Ihe habit ol feasting on tubercu- losis spvlm "i< other discharges ol those sick w.lh infectious diseases, and What To Do To Get Rid or Flies. Screen vow windows and doors. Do u earl, before II, Time and keep i kenmg Ihe room allowing onl, r, ol light to enter" i de. Flies ,n attempting to escape Ihe fumes will set Eliminate the Breeding Places of Flies. ftiet breed in tilth allow no filth or deca,ing matter ol an, ku FLIES IN THE HOME INDICATE A CARELESS HOUSEKEEPER REMEMBER NO DIRT- NO FLIES r^ w;, %.* V 9 A * ,>?f' l *i**~ i ^*z * - EXTRACTS FROM THE INSTRUCTOR'S NOTE BOOK By S. Maria Elliott, Simmons College, Boston. Education is not knowledge alone. It is the de- velopment of the individual, and this development should make each person a force in the world. No one has a right to keep for himself alone that which another needs. This is pre-eminently true in the line of scientific education. If the material side of life rests upon the principles of natural science, then the knowledge of these principles should, as soon as ac- quired, be put into practice for our own good. But this alone is selfishness. It gives us power, but power wrongly applied to ignoble uses works havoc. Put any newly acquired knowledge into practical use for the benefit of humanity and the world is improved, while our own lives are enriched. In this way, there is a subtle truth in someone's definition of a scientist : "The man who thinks God's thoughts after Him." Our school of Home Economics has enrolled among students persons from the Atlantic to the Pacific, from Texas to Canada, and even from far-off Hungary. Some have the schooling of the grammar grades alone, others are in or have passed through colleges and even professional schools. Each has had a dif- ferent experience from every other and each may learn from his neighbor. 117 ii8 HOUSEHOLD BACTERIOLOGY The young girl in the Tennessee mountains may be able to give of her experience to the college profes- sor, while in between and among all grades a common bond of interest has been welded because of our com- mon studies. Nor does the enrolled student alone gain knowledge from this company of common workers. The in- structors are not barred out from this feast of good things. Through the tests, returned from all quarters and by so many persons of varied attainments, stand- ards of living and rich experiences, the instructors are helped to a broader outlook and if, originally they were able to write facts which might serve as guide- posts in daily living, by this time the index finger should assuredly be pointed toward many other helpful paths. Some one has said that a guide-post is that which tells others to go the way in which you will not walk. This we will not accept, but wherever any guiding finger seems to invite, let us take that path so far at least as it serves our purpose and conditions. Here are some of the directions in which the stu- dents of Bacteriology have walked and others may follow. The following report from Utah may inspire another to do likewise : "I have tried to put my newly acquired knowledge into practice around the home. For example, I am being more careful of our food products to keep them from dust. I have used a dampened cloth in dusting NOTES 1 19 and have tried to impress upon my mind in practical ways the principles of action of these three classes of micro-organisms." Definitions are said not to define, but who can im- prove upon this one from Kentucky? An infectious disease is "a disease which is contracted from disease germs which make a specialty of this work," and this is as true to facts, although more difficult to read aloud, "Bacteria are infinitely small, intensely ener- getic, enormously prolific protoplasmic micro-organ- isms." A little knowledge is not always a dangerous thing. One woman says, "I thought when I took up the first lesson paper that there was nothing in it I should ever understand, but now it looks so different." She had seen molds through a magnifying glass, and goes on to say, "At any other time I wouldn't have given it a look or thought." A guide-post which points decidedly in the direction of success reads-. "Thank you more than I can say for the severity of your criticisms on the answers I sent. I liked it and because of it feel more confidence in the whole course." From Ohio comes this report: "I did find a doctor in our town who .... helped me to see things. "I had an idea that the contents of the Petri dish might be viewed at once. . . . The doctor said "Yes, under the focus it would be as large as the state of Ohio." 120 HOUSEHOLD BACTERIOLOGY Perhaps there are other doctors in other towns who would be glad to help the people "to see things." Some inquiring minds met difficulties, however, in unexpected places. A student who was "as thirsty after information as ever" was discouraged for the time being by the fact that she had borrowed a micro- scope from a physician who was not recognized by the "regulars." The city bacteriologist who had promised to furnish "microbes" for examination under said mi- croscope refused "because the Board of Health wouldn't like it," if their cultures were used by a physician "who advertised." Disinfection needs no further explanation to one who has before her the picture which she describes in this way : "Some years ago while traveling in Mexico we had occasion to pass through a yellow fever dis- trict. Fearing that the disease germs might contam- inate the oranges peddled at the station by the Mex- icans and of which we wished to purchase, a member of the party sterilized the fruit on the outside by dip- ping them in alcohol and burning it off immediately." That yellow fever is transmitted only by the sting of a certain species of mosquito was not then proved. That there may have been other germs on the fruit is not at all unlikely and while the alcohol bath may have been sufficient, the fire was certainly an ingeniously sure method of sterilization. A practicing physician among the students says that she "wishes every wife, mother and home-maker could NOTES 121 and would have the advantage of this course of study. Scarcely an hour passes in the day when the prac- tical importance of the lessons is not brought to my mind." Having gained an insight into the value of the study of chemistry and cleaning, a good Samaritan was anxious to help others and used her influence to have valuable books on such subjects added to the town library. A wail comes sounding from Georgia : "The housekeeper's life is one round of activity here not only on account of the invisible pests, but those we can see, such as roaches, weevils, etc. These may abound in the north in the eastern part, but we never saw one in Mlontana." Happy residents of Montana if they have no visible pests, but we have not yet heard that in Montana bacteria are absent. Mrs. W. finds that strawberries and raspberrries put up uncooked "kept perfectly well so far as (yeast) fermentation was concerned." They molded but only on the surface. When this surface growth was care- fully removed, there was no taint present. From the deck of a houseboat on the Mississippi, in the midst of a cruise of 1,200 miles, comes the state- ment that there bacteria die, "for even the dirt aboard exercises too much to settle down to idleness and mis- chief." Fresh air and sunshine Nature's best disin- fectants should certainly be found on such a vacation trip. 122 HOUSEHOLD BACTERIOLOGY An interested man adds the bit of information which may inspire others to experiment, possibly with success. He says they "have often in Kansas tried to pre- serve figs by canning them but thus far we have failed. Had to preserve them in sugar." An affirmative answer must certainly be given to the pertinent question : "Do not tooth brushes and wash cloths contain microbes?" They certainly do unless carefully cleaned. The former should occasion- ally have a bath in borax water. The latter should be well dried daily in the sunshine, if possible, and fre- quently boiled. There need not and should not be the putrid brush and the sour cloth. The sponge is a very difficult article to keep sweet and clean by common methods. The cloth is certainly much to be preferred from the standpoint of cleanness. The suggestion is not a bad one that "gloves be worn always while shopping." We may suggest that these gloves might well be washable. How much healthier our homes would be if we would take the advice of Mrs. W. and "do away with the unnecessary ornaments, merely dust collectors . . . . dispose of them and train the eye to sim- plicity and healthful emptiness." Along the same line is Miss G's decision : "I have been very much tempted of late to give up my rugs and mattings and use carpets, but I feel now that it would be taking a backward step." It would be better, if it were pos- sible, to do away with the matting which unless the NOTES 123 dust be wiped off from the surface instead of pushed through with the broom, will store much dust under- neath. Miss R. of Illinois has learned that one element in 'Vital resistance" is to keep one's self in good health, "for then my tonsilitis germs wouldn't have de- veloped." This is her decision after having spent a part of the "Glorious Fourth" in bed in the study of Part II. One of our students in Michigan has experimented in the sterilization and canning of milk, "using a solu- tion of salt to increase the temperature of the water." She found that by repeating this process three succes- sive days the milk would and did "keep over three years and would have kept indefinitely except for an accident." An enthusiastic teacher from Canada who "enjoys bacteriology heartily," performed not only the expe- riments with dust gardens but also numerous others, with most satisfactory results. Her enthusiasm and success may well be passed along for the benefit of others. One of her best results in growing molds came from a medium of ten per cent prune juice, ten per cent gelatine with eighty per cent water. This was ex- posed for twenty minutes. In a week there had grown "about twenty mold colonies" and five of bacteria. Another garden was made like the above, substitut- 124 HOUSEHOLD BACTERIOLOGY ing jelly for the juice. In this the bacteria flourished better than the molds. One of the gardens which she tried was turned to liquid in a week. She was fortunate to receive from a bacteriologist a pure culture of b. prodigiosus or the "miracle germ." This she planted in the yolk of a hard-boiled egg and in a week it had transformed the yolk to a red mass mingled with much liquid. This was well covered and kept in darkness. She one day found that the hecto- graph had become a garden of molds and bacteria. Under the right conditions it might have been lique- fied. That childen can be readily taught by observation is shown by a report from the same teacher. A girl insisted that her hands were clean, but a tablespoon of the water in which she washed her clean hands when introduced into milk proved an efficient aid in its putrefaction. "The cooking class never forgot to wash their .hands." A class of farmers' daughters found many sugges- tions for their future care of milk products from va- rious experiments in the cultivation in milk of the dif- ferent species which turn it sour, putrid, bitter, etc. Such reports as these should stimulate other teach- ers to interest, to instruct, to educate, by similar ex- periments, the children under their care. Anything which will raise the standard of personal cleanness or that of food supplies and general house conditions will tend toward health and greater economy. NOTES 125 And so the tests and personal letters continue to encourage the instructor and open up many a vista of unexpected applications or suggested truths. The variety of questions show the great need of the study even among those favored with high scholarship as well as among those trained in the thorough but slower school of experience. When many facts of everyday life, of common ob- servation, are seen to be caused by the growth of omni- present, invisible plants put into the world as benef- icent agents, all life becomes more interesting. Such study should lead away from foolish or ungrounded fear. It should lead to thought and wise action, that the danger spots be prevented or removed; that each do all in his power to protect not only himself but his neighbor. How strongly it emphasizes the truth from the great poet-philosopher, John Milton: " Not to know at large Of things remote from use, But to know that which Before us lies in daily life Is tne prime wisdom." SAFEGUARDS OF THE BODY AGAINST DISEASE* By T. Mitchell Prudden. Author of "Dust and Its Dangers," "The Story of the Bacteria," etc., etc. Among the shibboleths of physicians one of the more recent and perhaps the most widely popular to- day is the word immunity, relating to infectious or bacterial disease. The subject holds the floor in the learned societies ; it crams the medical books and jour- nals ; it lures the solitary workers in the laboratories to long and toilsome quests. At last the layman has begun the query as to what it is all about, and how the new lore which filters through the magazines and newspapers out to him may affect his chance for the healthful threescore years and ten which is his birth- right, but of which he is too often ruthlessly deprived. It is really worth while for everybody to know something about immunity to infectious diseases. For the new doctrines and their practical applications in the workaday world are full of promise for the preven- tion and cure of the infectious maladies, if only the public will bear its part with intelligence and zeal. The beginning of the story goes back more than a quarter of a century, when the notion still lingered on that disease was a mysterious something apart from *Reprinted from The Outlook by permission. 127 128 HOUSEHOLD BACTERIOLOGY the body machine, which with sinister intent took pos- session of our interiors and battled for our lives ; or was a visitation of Providence about which we might not inquire too curiously. Then suddenly we became aware that the soil, air, and water, the surfaces of plants and of our own bodies were swarming with minute, invisible, living beings, some few of which were of the greatest importance to man because they were capable of inciting serious disorders. By a tech- nical device of the laboratory it was soon found pos- sible to secure these invisible plants from their various sources, to separate them one from another, and to cultivate and study them with as much precision as the farmer grows and gathers his various crops. Of course at first the few harmful members of this newly exploited group of living things cast a shadow over all the rest. And we shuddered as the pioneer in this new domain of science revealed the thousands and tens of thousands of bacteria which we might be swallowing with our glass of water or with our bunch of grapes. But we were soon reassured, for we were told that we had nothing to fear from the rank and file of our humble, newly discovered commensals ; that, on the contrary, they were our friends, without which, indeed, the world of life could not long continue. It was only the few which we must avoid if we would steer clear of tuberculosis, pneumonia, diphtheria, ty- phoid fever, cholera, and a dozen or so others of the uncanny brood of infectious, diseases. NOTES 129 These disease-producing germs the bacteriologist soon came to know very well as he grew them in the safe purlieus of his laboratories and found out the various ways in which they were able to work havoc in the delicate mechanism of their earth-neighbor, man. Thus the nature of disease became clearer and the problems of its prevention and cure definite and precise. BARRIERS OF THE BODY. The healthy human body is safe-guarded in many effective ways against the entrance and continued life of bacteria and allied organisms. The tough skin affords a most impregnable barrier. The nose and throat and the tubes leading to the lungs are protected with various mechanisms barring the way to many germs which dusty air bears in every breath. The complex chemical processes in our digestive apparatus which convert our food into building material for brain and muscle spell death to the myriads of bac- teria with which our uncooked foods are mingled. So, altogether, our life among bacteria, even those of the deadly sort, is usually exposed to little hazard. But when the best is said, these minute inciters of disease do now and then win their way to the intimate recesses of our bodies, producing serious results. The measure of their ravages is found in the tables of the statisticians, which show that a large proportion of all who die fall victims to these invisible foes, and that, too, at an age when life holds out its brightest promise. 130 HOUSEHOLD BACTERIOLOGY Now let us see how these germs are able to do such serious damage in the living body. This body is made up of a bony framework, around which various tissues and organs are securely and compactly grouped. Each one of these tissues and organs is composed of tiny structures called cells. The cells are little centers of energy stored up from the food we eat and the air we breathe little laboratories in which chemical pro- cesses of the most subtle character are constantly go- ing on. And the life of the body is simply the sum of the more or less independent but co-ordinated lives of the cells which compose it, all acting in har- mony. * * * All these delicate and exquisitely adjusted elements of the body are able to adapt themselves to many vicissitudes without serious disturbance to that sensi- tive equilibrium which we name health. We may starve them, surfeit them, overwork them, and poison them in the most abandoned fashion. But they sway back to their respective tasks again when our abuse ceases. Unless we go too far; and then they may struggle on, but only in the halting, perverted way which we call disease. Now, what happens when into this happy family of cells, each nicely adjusted to the others, and all en- gaged in their various tasks, living bacteria enter, hav- ing escaped the outer safeguards ? But before we try to discover this, let us brush away a few cobwebs. SAFEGUARDS OF THE BODY 131 NATURE OF DISEASE We are so. accustomed to personify disease, to think of it as a visitation of malign forces, and to talk of it in terms which belong in the era of superstition and personal devils, that clear notions of disease as a process, not a thing, are rare indeed. Disease is a perverted process of the living body cells. Bacteria are not the disease; they are only the inciters of disease; nor do they enter the body with sinister intent. If the chances of the hour bring them to rest among the living body cells, and if the condi- tions are favorable, they begin to grow, but with just as little purpose for good or evil as if they had lodged upon the surface of a rotten turnip. Many of the bacteria which enter the body do not grow at all. The soil is not to their liking, the envi- ronment is not congenial ; they die and are hustled off forthwith by certain lowly organized cells phago- cytes we call them which are the scavengers of the body, and are ever moving here and there to keep the tissues clear and clean. Many bacteria, on the other hand, find in the living body conditions suitable enough, faute de mieux, for their simple life processes. But they are speedily devoured and digested by the scaven- ger cells, or are killed by destructive body juices, and so their tragedies end. But there is another side to the story when the bac- teria which are stranded within the tissues are not to be tolerated in a well-organized cell family. Then trouble begins. I 3 2 HOUSEHOLD BACTERIOLOGY We are likely to think that because bacteria are so small and lowly they cannot do much. But in fact they do a great deal. Their life processes are ex- tremely complex. They are chemical engines of great potency. Out of the food which they assimilate they manufacture a host of subtle poisons, some of which are stored up in their tiny bodies, some set free into the fluids of their hosts. This, in fact, is the front of their offending: the poisons which they elaborate and set free damage the cells. Sometimes these poisons interfere with the neces- sary performances of the cells close about them, or they harm them, but not irretrievably; or they may kill them forthwith. Again, they are carried far and wide throughout the body, and the heart is enfeebled, the brain palsied, or fever dominates the scene. This is the situation, then, when disease-producing bacteria get in among the living body cells and begin to grow, setting free their powerful poisons. It is cell against cell the well-bred, highly differentiated cell of the body against the crude, prolific spark of matter way down upon her borderland of life, potent only to eat, to multiply, to shed abroad its poison. But the weapons of both the combatants are poisonous. For we should not permit our sympathetic viewpoint to obscure the fact that the fluids and the digestive juices which our own cells elaborate are poisons for bacteria, quite as much as is their stuff for us. It is the old story of the survival of the fittest here in this SAFEGUARDS OF THE BODY 133 little hidden arena. A new environment is estab- lished both for the body cells and for the bacteria ; and what we dramatize as a battle is really only the at- tempt of each to adapt itself to the new conditions furnished by the other. The one which adapts itself most readily and completely and quickly wins, by survival. Infectious diseases, then, are those which are in- duced by the entrance into the body and the multipli- cation there of disease-inducing micro-organisms. These are most frequently bacteria ; but other lowly beings, such as yeasts and minute animals called pro- tozoa, are sometimes to blame. Each of these infec- tious diseases has its peculiar characteristics by which physicians recognize it. These features are especially dependent upon the nature of the bacteria which in- duce them : their ways of growing, the nature of the poisons. which they set free, their tenacity of life, etc. But the body cells have their particular vulnerabilities to bacterial poisons, so that in one case it is the nervous system, in another the lungs, in another the digestive apparatus, which especially suffers. Moreover, as one rose is redder than another, or one aromatic plant more pungent than its fellow, so in one case the bac- teria which gain access to the body may evolve a more potent poison than in another, and then the dis- ease may be of a more virulent type. So also an individual may at the time of infection be much more susceptible to the ravages of the germ than is usual, and thus the victim of a graver form of disease. 134 HOUSEHOLD BACTERIOLOGY Now we come to immunity. We have seen that, under the usual conditions, the body may be capable of disposing of bacteria or other microbes which enter it by means of its cells or its fluids, so that the in- vaders can do no harm. This condition is called here- ditary immunity an immunity which is born with us. There is a good deal of difference in animal species in this respect. For many bacteria which are deadly to some of the lower animals are harmless to man, and vice versa. So also among the lower animals them- selves some are susceptible, some not, to the same species of bacteria. But there is another phase of immunity which we must look at a little more closely, called acquired im- munity. It is a very old observation of the doctors, which has become part of the lore of the layman, that there are infectious diseases in which one attack, if recovered from, protects its victim for a longer or shorter period against a subsequent attack. This is true of smallpox, measles, scarlet fever and in less marked degree of typhoid fever, diphtheria and others. Here is a form of acquired immunity secured through an experience of the disease itself. In fact, re- covery from an infectious disease can take place only by the establishment of an immunity which did not pre- viously exist. But this acquired immunity in some in- stances suffices only for the exigencies of the hour, while in others it persists for some time, precluding fresh infection. SAFEGUARDS OF THE BODY 135 In order to understand what has happened in the body of a person who has thus acquired immunity through a successfully weathered attack of an infec- tious disease, it will be necessary for us to look at some very remarkable achievements of the past few years in the prevention and cure of diphtheria. For, though the fact of immunity acquired through disease has been known so long, no one until recently could offer even a plausible conjecture as to the reason for it. Among the earlier of the disease-inducing bacteria to be discovered, some twenty years ago, was the bacillus of diphtheria. This is a little rod-like plant found only in connection with this disease, or in those who have been exposed to it. It is readily cultivated in the' laboratory, being very fond of beef tea, in which it is commonly grown. When a few of these living bacilli from the culture are put beneath the skin of animals, such as rabbits or guinea pigs, a fatal disease is induced, essentially similar to the disease diphtheria in man. In the early days of bacteriology it was believed that, in order to induce artificially the symptoms of an infectious disease, the living germs must be put into the body, and grow there. But it was presently discovered that if you separate all the germs from a culture of the diphtheria bacillus, and introduce the beef- tea in which they had grown for some time, into an animal, you can induce the symptoms of the disease just as well as if the germs themselves are put in. 136 HOUSEHOLD BACTERIOLOGY Thus was revealed the significant fact that bacteria may damage the body quite as much by the poisons which they elaborate as by their direct presence. Now came the next step in the upbuilding of this remarkable series of discoveries. It was found that if this beef tea in which diphtheria bacilli have grown, and which contains the germ-poison, be introduced into an animal, at first in very minute quantities, which are gradually increased in subsequent doses, the ani- mal grows more and more tolerant of the poison, until at last he sustains with indifference amounts which, if given at first, would have been certainly and speedily fatal. In other words, it was found that by the use of the poison alone of the diphtheria bacillus in increasing doses, an animal can be rendered artificially immune without having suffered from the disease diphtheria at all. But now a most incredible thing was discovered. It was found that if the blood be drawn from an ani- mal thus rendered artificially immune, and allowed to clot, the yellowish, watery fluid which separates from the solid part, and which we call blood serum, contains something which, when the serum is intro- duced into the body of another animal, perfectly pro- tects him, not only from the poison of the diphtheria germ, but from the living germ itself ; in other words, enders him, too, immune.. SAFEGUARDS OF THE BODY 137 ANTITOXIN. This curious something so potent and so beneficent was called antitoxin, because it acts by neutralizing or abolishing the harmful effects of the toxin that is, the poison of the diphtheria germ. No chemist has ever been able to separate antitoxin from the blood serum ; no man knows its composition ; but there it is, the heart, it seems, of the mystery of immunity. One might think that we had found here some re- markable cure-all in this antitoxin, and that it would prevent or cure other infectious diseases. But this is not the case. It has no more effect in the preven- tion or cure of other diseases, such as pneumonia, typhoid fever, etc., than so much water. In other words, its action is specific. The seeker of light in fields relating to medicine is rarely free from the consciousness of urgency in the solution of his problem. So the moment he found that he could protect the lower animals against the ravages of diphtheria which he had artificially induced, he turned at once to the possibility of human protec- tion and cure. And the situation was indeed urgent. No disease was more dreaded than diphtheria, espe- cially in children ; the suffering of the victims was pitiful, the mortality great. The first experiments were made on small animals, but if the serum were to be used in children larger quantities would be required, so sheep and goats were 138 HOUSEHOLD BACTERIOLOGY immunized. But these did not furnish enough. So at last the horse was tried, and was found admirably adapted to the purpose. He lends himself readily to the increasing doses of the potent diphtheria poison ; he is easily rendered immune, and he furnishes without especial inconvenience a large quantity of blood. In fact, he makes no more fuss about losing blood than did the old people along in the early part of the last century, who were quite accustomed in the springtime, when they felt a bit heavy and had a little headache, to drop into the nearest barber shop to be bled. The preparation of diphtheria antitoxin has been brought to a high state of perfection. The horses are first very carefully tested so as to be certain that they have no disease. They are well fed and groomed, and suitably exercised. At first a small amount of the diphtheria toxin is injected beneath the skin. After a few days a larger dose is given, and then at intervals larger and larger quantities, until at last the horse is receiving such an amount in a single dose as if given at first would have sufficed to kill not only one but many horses. He has not had diphtheria at all, but he is now poison-proof immune. The animal is then bled from the large vein in the neck, the greatest care being taken, by cleansing of the skin, the use of sterilized instruments, etc., that no outside germ shall get into the blood as it flows. This blood is set aside in a cool place, and presently, as the clot forms, the serum separates in considerable quan- SAFEGUARDS OF THE BODY 139 tity. This is drawn off into flasks and contains the precious life-saving stuff, antitoxin. Since no one has been able to separate this anti- toxic substance from the serum, it is necessary, in order to find out how powerful it is for its virtue varies with every horse to have recourse to quite un- usual methods. It cannot be weighed as the druggist weighs rhubarb or camphor. But as its value depends upon its powers to neutralize the action of the diph- theria poison in living animals, the test of its strength must be made on these. Guinea pigs are usually em- ployed. It is thus learned how much of the antitoxin to be tested is necessary to save the life of the animal which has received a fatal dose of the diphtheria poison. The amount necessary for the protection of a human being is larger in such proportion as his weight is greater than that of the guinea pig. The saving power of each specimen of antitoxic horse serum having been thus determined, it is carefully tested to see that no contamination has taken place, then it is divided into the proper doses, each in a small sealed bottle, and sent out upon its mission. This antitoxin is not effective if given by the mouth, as many drugs are; but it is introduced beneath the skin by a small syringe, and is speedily absorbed into the body fluids. Now, what has been accomplished by the use of this new and curious form of medicine? The mortality 140 HOUSEHOLD BACTERIOLOGY from diphtheria, taking the results the world over and in a general way, has been reduced more than 50 per cent, and, under the most favorable conditions, full 75 per cent. I need not dwell upon the significance of this beneficent result in the saving of life and in the relief of suffering. But there is another way in which diphtheria anti- toxin has been of the greatest value ; that is, in the prevention of the disease among those who have been exposed to infection in families, schools, and other pub- lic institutions. Under these conditions an injection of the antitoxin beneath the skin has been the means of warding off an attack of the disease in groups of persons, some of whom without it must inevitably have We should be most ungrateful if we failed to recog- nize the importance of this new relationship which has been established between ourselves and our old and ever-useful friend, the horse. We make him manu- facture for us in the department of his interior that protective stuff which we could otherwise secure only by ourselves sustaining an attack of diphtheria, and this, too, with the chances against success. We are now prepared to inquire how this curious antitoxin acts in the body to produce these truly mar- velous effects. Has the body kept secreted all through these years of evolution some special mechanism, or some chemical potency, by which all of a sudden it can protect itself against so subtle and so special a poison as this roving bacillus ? And if so, do we keep SAFEGUARDS OF THE BODY 141 on hand in our mysterious insides the latent power of protection against all the special forms of disease- producing bacteria which wander the earth? How does it fit into physiology ? Or can we indeed create new protective powers in the stress of such varied accidents as new infections involve? We have seen that the diphtheria bacillus produces its deadly effects through a poison which it sets free as it grows in the body. In order to understand how this poison is rendered harmless, we must know how it damages the delicate body cells. So we must go back to the cell for a moment. These cells in the living body sit in their respective places, and as the nutrient fluids pass and bathe them, each of them being a powerful little chemical factory, they seize up- on whatever nutrient molecules they require, and out of these build up such new substances as they need in their business, whether this be self-nutrition, or the storage of energy, or the furnishing of special life- stuff for their neighbors. So each cell is armed with this power of forming chemical union with the food. But suppose something comes along in the body fluids with which the cell can and does form the same sort of chemical union, but which is not a food; on the contrary, damages the cell that is, is poisonous or toxic for it. The cell suffers, of course first, by the direct damage, and, second, by the loss of its food-securing capacity. The latter it has used up in uniting with the poison. 142 HOUSEHOLD BACTERIOLOGY Now, the cell so runs the theory finding itself deprived of its food, produces a new and increased amount of this food-seizing substance. In fact, in accordance with a well-known law in pathology, it produces such a surplus of this substance that it is cast off into the body fluid. But this food-seizing substance, now produced in superabundance and cast off, is still capable of uniting with the poison which is circulating in the body fluids. This it does, and as molecule by molecule the poison forms the new chemical union it is neutralized and so prevented from coming in contact with the cells, where alone it can do harm. This is antitoxic im- munity. Now, if more of this stuff is given off by the cells in the emergency than is necessary to render all the poison harmless, the excess in the body fluid remains there as unused antitoxin. This is the condition of the immuned horse. His cells have produced more antitoxin than is necessary to protect himself, and we draw off some of it in the blood and^ use it to save the child. Thus we see that this curious protective process is not an incredible anomaly, but that the body cells have availed themselves in an emergency as protective agencies of those capacities which under normal con- ditions they use in the assimilation of their food. This power of the body to protect itself against the poisonous products of bacterial life may be exerted SAFEGUARDS OF THE BODY 143 in a similar way in the presence of other 'poisons. Thus certain poisonous vegetable extracts and the venom of snakes may be used to secure artificial im- munity in the horse, with the development of antitoxin. In countries where venomous reptiles abound the loss of life from their bites is sometimes very great; for example, in India, where the great cobra slays many victims. An antitoxin for snake poison is now made which is most effective against the bites of the cobra and several other venomous serpents. It is called antivenin. Its efficiency for rattlesnake bites has been claimed, but recent studies have thrown some doubt upon this point. Of course as soon as this remarkable diphtheria antitoxin was discovered the eager workers in the field of preventive medicine at once concluded that we were at the dawn of a new day. For if we can so effectively control the ravages of diphtheria, why not of the other bacterial diseases? So everybody set to work to discovfir new antitoxic sera of pneumonia, tuberculosis, plague, typhoid fever, cholera and vari- ous forms of blood poisoning, 'the bacterial excitants of which were already known. But, unfortunately, these efforts, pursued with the utmost zeal and persistence the world over, have thus far met with very little success. Antitoxic sera for tetanus, or lockjaw, and for some forms of blood poisoning, have seemed to be measurably useful. But, for the most part, the attempts have failed, except in 144 HOUSEHOLD BACTERIOLOGY the daily newspaper, for which the discovery overnight of a new "serum" seems to furnish an item of per- petual interest. The reasons for this failure are in part evident to experts in this field, in part are still very obscure, and are too technical to be entered upon here. But the eager and toilsome search goes on with such inspira- tion as is ever his who deals with these urgent prob- lems of life and death, and at any moment the key to the riddle may lie in our hands. It would be interesting, did the scope of this article permit, to look at the means by which the body pro- tects itself against infection, not by neutralization of poisons, but by the actual destruction of the poison producers the bacteria themselves. Suffice .it to say that here also, in this bacteria-destroying phase of immunity germicidal immunity, it is called the body does not command new forces or mechanisms, but makes use of those which are maintained for its daily service, but which in the emergency it wields to new ends and with exalted energy. OTHER METHODS OF PROTECTION. When it was found that it was not possible at once to secure antitoxic sera for other infectious diseases in the w^ay which had been so successful with diph- theria, the attempt was made to obtain protection in some other way. The leading idea in these researches was to find a method of adapting man to pathogenic germs without exposing him in the process to the VACCINATION 145 risks of the disease. Some bacteria seem to produce their harmful effects not so much by the poisons which they set free as by something stored up in the bodies of the germs themselves. But if the living germs are put into the body, they may cause the disease, and the very thing to be guarded against might thus be precipitated. So the attempt was made to avoid this risk by kill- ing the germs by heat and then injecting these dead organisms beneath the skin of the person to be pro- tected. This method has been practiced on a large scale in some countries with the typhoid fever bacillus and with the bacillus of the plague. While some meas- ure of protection seems to have been secured in this way, the method has not been very generally adopted. There are two other forms of artificially induced immunity which we must consider briefly, since they belong among the greatest life-saving agencies at our command today. I refer to vaccination for protection against smallpox and the preventive inoculations for rabies or hydrophobia. VACCINATION First, vaccination to prevent smallpox. If the good Dr. Jenner, who more than a hundred years ago did some excellent observing and some clear thinking about what he saw, and found out how to prevent smallpox, could listen to our up-to-date talk about bac- teria, microbes, toxins and antitoxins, and various phases of immunity, he would not understand a word 146 HOUSEHOLD BACTERIOLOGY of it. But, just the same, he led the way to the prac- tical banishment through artificial immunity of one of the greatest and most dreaded scourges of man. It was known in Jenner's time that those who milked cows having sores upon the udder, due to a local affection called cowpox, often acquired similar sores upon their hands. These soon healed, involving only a slight illness. But such persons had become partially or wholly immune to the more serious disease of man, smallpox. Jenner studied this subject carefully and came to the conclusion that artificial inoculation with a very small portion of material taken from such cattle might be practiced on a large scale with beneficent results. In spite of much opposition he urged his views, which were gradually accepted, until at last the method has become almost universal in civilized communities. Large and carefully managed establishments are now devoted to the preparation of the virus, as it is called, by which artificial immunity to smallpox is se- cured. The slight affection of animals calves from which the virus is taken. is called vaccinia, while the disease corresponding to it in man, smallpox, is called variola. The method now practiced on the large scale is very simple. Healthy calves are carefully cleansed and kept in clean, airy stalls. The belly is shaved and most scrupulously freed from all possible sources of con- tamination. Into this clean surface, slightly scarified, VACCINATION 147 is rubbed some of the virus secured from previous cases. After a few days this surface furnishes a yel- lowish, watery material which contains the protective stuff. This is gathered and mixed with glycerine, and, after careful tests of its purity, is distributed to physi- cians in small sealed glass tubes. This virus rubbed on to a scratched surface of the human skin induces a slight sore, sometimes accompanied by a little ma^ laise, and then heals. By this process the liability to smallpox is very greatly diminished, but the protection is reduced as time passes, so that revaccination is necessary if the fullest protection is to be secured. It is certain that smallpox is an infectious disease induced by some form of micro-organism. But the exact character of this is still unknown. Attempts to cultivate it have thus far failed. It appears that the unknown organism suffers diminution in virulence by passing through the body of the relatively insuscepti- ble calf, and in this condition, while incapable of in- citing smallpox in man, is still potent to establish immunity. A good deal of opposition has developed here and there to vaccination even in recent times. This has been based partly upon the fear lest foreign and noxious material should be introduced into the body along with the virus. But if it be carefully prepared, this fear is groundless. While accidents are not im- possible, the ill effects which now and then appear are 148 HOUSEHOLD BACTERIOLOGY usually due to the handling or rubbing of the little wound by dirty persons, against the warning of the physician. Largely as the result of this form of preventive inoculation, smallpox is no longer to be seriously dreaded. In fact, in the graphic charts which the statisticians make out to show the relative frequency of various diseases, the lines showing smallpox are so short that you can hardly see them ; while it is those representing tuberculosis, pneumonia and other dis- eases of the respiratory system which stretch in most disquieting fashion across the page. HYDROPHOBIA Rabies, or hydrophobia, is one of the most dreaded of human maladies, and one whose victims in former times no medical skill could save. It is an infectious disease, though the micro-organism inducing it is still undiscovered. Hydrophobia is commonly acquired by man through the bites of rabic animals, in this country most frequently the dog. The unknown infectious agent is present in the saliva of affected animals. It travels along the nerve trunks from the site of the bite to the central nervous system, where it especially concentrates itself. Pasteur, the great master in the solution of knotty problems relating to bacteria and immunity, spent many toilsome and harassing years in the study of the rabic virus and in attempts to devise an effective method of protection. He found at last that, although he could not isolate the microbe, he could transmit HYDROPHOBIA. i 49 the disease from animal to animal by inoculating into the nervous system of the well animal a tiny portion of nerve tissue from one which had succumbed. The inoculated animals invariably died at a fixed period. After a long series of studies which we cannot here review, he discovered that if the spinal cord of one of the inoculated animals (rabbits) which had died be dried in a clean place, it gradually lost its virulence, so that whereas at first it invariably killed in seven days, day by day it lost its power, so that after drying for fourteen days it was quite inert. Given thus a virus ranging gradually from the very feeble up to the strongest, he saw the possibility of gradually ac- customing the body to the stuff, so that at last it would resist the very strongest. This was tried on dogs, and it was found that after this gradual adaptation to the virus they became at last wholly indifferent to the bites of mad dogs or the artificial inoculation of the strongest virus. The principle was finally applied to man, with the most remarkable and satisfactory results. Rabies is peculiar in that a long period usually elapses between the bite of a rabic animal and the development of symptoms. This period, called the in- cubation period, is in man on the average from thirty to forty days; so that if the preventive treatment be instituted without undue delay, there is usually time for the adaptation of the subject to the artificial virus. This accomplished, the disease does not occur. 150 HOUSEHOLD BACTERIOLOGY At each laborotary where the treatment for the pre- vention of rabies is carried on, this material of vary- ing degrees of potency is kept constantly ready, so that as soon as possible after a bite from a supposed rabic animal the treatment may be started. The oper- ation is a simple subcutaneous injection, resulting usually only in a slight or temporary local soreness. The whole affair is completed within two weeks, when all apprehension may be dismissed. No untoward ef- fects follow the treatment. The mortality from hydrophobia before the day of preventive inoculation was about 16 per cent. Through this treatment it has been reduced to about two-tenths The methods of securing artificial immunity to in- fectious diseases, which we have so hastily surveyed, widely different as the details may be, all seem to depend upon the same wonderful power of the body cells to adapt themselves to harmful conditions by the use to new ends of the old physiological capacities. The task of the investigator centers largely in dis- covering the ways in which the body cells may be educated to their new responsibilities with safety and despatch. We seem to be just at the dawn of discovery in this newly opened field, and the outlook is of the highest promise for the relief of suffering and the prolongation of life. The various preventive means already devised are in the hands of experts and require the greatest care SAFEGUARDS OF THE BODY 151 on the part of those who make the preparations and skill and judgment in those who advise and administer them. With these things "the man in the street" has nothing to do. But it is for him to see to it that no fad or ism, no false guides, nor ignorance, nor indif- ference shall hold him from seeking and following wise medical counsel in the face of any of the mala- dies from which artificial immunity may be secured today. Here ignorance is folly, indifference, crime. On the other hand, it should not be forgotten that underlying all these protective measures is the living body machine, which each controls for himself. If, through the various phases of unwholesome living so largely in evidence today, the machine is lacking in vigor, then by so much are the chances of recovery lessened when the shadow of disease falls across our path. Not too much work nor too much play; not too much food and drink, but enough ; good air and in- telligent cleanliness in houses, assembly places and public conveyances if these conditions be fulfilled in such way and measure as the hygiene and sanitation of the day demand, we shall go far to establish our birthright to threescore years and ten. And our im- munity to infectious disease, whether we brought it into the world with us, or achieve it under the minis- trations of the physicians, will most closely confirm the promise of science. BIBLIOGRAPHY '53 BIBLIOGRAPHY Bacteria, Yeasts, and Molds in the Home, by H W. Conn. ($1.00, postage loc ) The Story of Germ Life, by H. W. Conn. (350., postage 6c.) Dust and Its Dangers, by T. Mitchell Prudden. (750., postage 6c) The Story of the Bacteria, by T. Mitchell Prudden. (750., postage 6c.) Drinking Water and Ice Supples, by T. Mitchell Prudden. V7SC., postage 6c.) Our Secret Friends and Foes, by Percy Frankland. ($1.25, postage i2C.) Bacteria, by George Newman. ($2.00, postage i8c.) Bacteria and Their Products, by G. S. Woodhead. ($1.50, postage 140.) Clean Milk, by S. D. Belcher. ($1.00, postage IDC.) Note: The above books may be borrowed by members of the School for the cost of postage. For Advanced Reading A Laboratory Guide in Elementary Bacteriology, by Wm. Dodge Frost. ($2.50.) Bacteriology and the Public Health, by George Newman. ($S-oo.) Immunity in Infectious Diseases, by Metchnikoff. ($5.25.) Technical Mycology, by Dr. Franz Lafar, 2 vols. ($8.00.) Micro-organisms and Fer.nentation, by Alfred Jorgensen. 1 54 HO USEHOLD BA CTERIOL OGY Government Bulletins Free of the Department of Agriculture, Washington, D. C. FARMERS' BULLETINS No. 29 Souring of Milk and other Changes in Milk Prod- ucts. No. 42 Facts about Milk (revised). No. 43 Sewage Disposal on the Farm and the Protection of Drinking Water. No. 57 Butter Making on the Farm. No. 63 C~re of Milk on the Farm No. 73 Experiment Station Work IV, Pure Water. No. 84 Experiment Station Work VII. Cured Test for Clean Milk. No. 92 Experiment Station Work IX. Pasteurization in Butter Making, etc. No 107 Experiment Station Work XIII, Ropy Milk and Cream. No. 124 Experiment Station Work XVII, Soil Inocula- tion, Distilled Drinking Water. No. 155 How Insects Affect Health in Rural Districts. No. 162 Experiment Station Work XXI, Purifying Milk by Centrifugal Separation. No. 1 66 Cheese Making on the Farm. No. 175 Home Manufacture and Use of Unfermented Grape Juice. No. 210 Experiment Station Work XX VII, The Covered Milk Pail. No. 214 Beneficial Bacteria for Leguminous Crops. No. 227 Experiment Station Work XXX, Clean Milk. No. 233 Experiment Station Work XXXI, Cider Vinegar. BIBLIOGRAPHY 155 No. 240 fnoculation of Legumes. No. 241 Butter Making on the Farm. No. 262 Experiment Station Work XXXVI, Water for Table Use. Canning by Intermittent Sterili- zation. CIRCULARS OP BUREAU OF ANIMAL INDUSTRY No. i Directions for Pasteurizing Milk. No. 19 Factory Cheese and How it is Made. No. 52 A Chemical Examination of Various Tubercle Bacilli. No. 57 Invisible Microorganisms. No. 70 Tuberculosis of Cattle. No. 83 Danger of Infection with Tuberculosis by Dif- ferent kinds of Exposure. No. 91 Bacillus Microphorus and its Economic Importance. REPRINTS FROM YEAR BOOKS No. 192 Rabies: Its Cause, Frequency, and Treatment (1900). No. 221 The Use and Abuse of Food Preservatives (1900). No. 262 The Contamination of Public Water Supplies, by Algae (1902). Bacteria and the Nitrogen Problem (1902). SUPPLEMENTAL PROGRAM ARRANGED FOR CLASS STUDY ON HOUSEHOLD BACTERIOLOGY By S. Maria Elliott, Simmons College, Boston MEETING I (Study pages 1-14) Dust and Dust Gardens The growth of a dust garden will impress this whole sub- ject much more vividly than any amount of reading. Each member should plant and watch the growth of at least one garden. One person might prepare and sterilize the nutrient gelatine for the class, distributing in sterilized wide-mouth vials or test tubes about two teaspoonfuls to each. Each member should sterilize the dish or dishes, melt the gelatine by placing the tube in cold water and then heating it, pour into the Petri dish, cover, cool, and plant. (If not to be had locally, a dozen Petri dishes may be obtained through the School for $1.90, a half a dozen for $ i . oo, not including express charges. Money will be refunded for those returned. ) Arrange as varied conditions for experiment as possible. The following list is only suggestive of interesting sources and methods of treatment: (a) After sweeping a carpeted room with a dry broom, expose five minutes, keep at room temperature, but not in direct sunlight. (b) Same as above but kept in a refrigerator. (c) Same as "a" but shut up in a box. (d) Dig out from some corner of stairway or room the dirt which was overlooked in cleaning. Pulverize this and scatter a little over the jelly. Keep in any condition desired. (e) Let a fly walk over the media. 157 158 HOUSEHOLD BACTERIOLOGY (f) Touch the fingers to the jelly after handling dusty books. (g) Touch the jelly with pieces of money or with a bill. (h) Take any one of the planted plates. Lay over one-half of the jelly a thick piece of black paper or cloth. Put the dish in direct sunlight, (i) Scrape a bit of the deposit from the teeth and touch it to several places on the jelly, (j) Rub a few drops of boiled water in the palm of the hand and mix it with the liquefied media. (k) Take one of the dishes to a public gathering and open it for five minutes or more when the audience has been seated for a short time. Require that each experimenter keep a daily record of every change, however minute. At the next meeting let these experiments be reported, the gardens shown, and as many conclusions drawn as may be feasible, leaving their truth or fakity to be proved by further study. References: Dust and Its Dangers, by T. M. Prudden. Chapters I, II, III, IV. (75C., postage 6c.) Our Secret Friends and Foes, by Percy F. Frankland. Chapters I -III. ($i. 25, postage I2C.) MEETING II (Study pages 17-32) Character of Bacteria If possible, get some physician to show bacteria under a microscope. (a) Take some from the dust gardens already planted. (b) Take a drop of water from a vase of flowers which has stood unchanged for a week. Put a wisp of hay in warm water, let it stand for twenty-four hours in a warm place, then examine with the microscope a drop of the brownish infusion. Make any experiments possible from "Bacteria, Yeasts, and Molds,'! by H. W. Conn, pages 269-285. STUD Y PROGRAM \ 59 Perhaps the physician may be able to show some pathogenic germs. References: The Story of Germ Life, by H. W. Conn. Chap- ter I. (350., postage 6c.) Bacteria, Yeasts, and Molds, by H. W. Conn. Chapters VIII, IX. ($1.00, postage loc.) The Story of the Bacteria, by T. M. Prudden Chapters I, II, III, and IV. (750., postage 6c.) MEETING in (Study pages 33-46) Molds and Yeasts (a) Show a sample of moldy bread, cheese, shoe, mildew from clothes. (b) Generate carbon dioxide as shown on page 43. (c) Examine both yeasts and molds under microscope or hand magnifying glass. (d) Make a small portion of "milk emptins" as described on page 6. Note changes which occur during one week. (e) Mix some bread dough. Put a part in the ice-chest, keep an equal part at about 70 F. and a third at a much higher temperature, 100 F. or over. Compare results at the end of six. twelve, and twenty hours. (f) Pour boiling water on a small bit of yeast cake and use this solution for mixing another portion of dough which is to be kept at about 70 F. References: Bacteria, Yeasts, and Molds, by H W. Conn. Chapter II, pages 12-24, and Chapters III, IV, V, and VI. ($1.00, postage loc.) (Select a composite set of answers to Test Questions on Part I and send them to the School for correction. Report on the supplemental work done and the results of the experi- ments.) i6o HOUSEHOLD BACTERIOLOGY MEETING IV (Study pages 49-62) Work of Bacteria Fermentation and putrefaction. References: The Story of Germ Life, by H. W. Conn. Chap- ters II III, IV. (350., postage 6c.) Bacteria, Yeasts, and Molds, by H. W. Conn. Chapters IX-XIII. ($1.00. postage IDC ) Our Secret Friends and Foes, by Percy F. Frank- land. Chapters IV, V. ($1.25, postage i2c.) See also U. S. Government Bulletins. MEETING V (Study pages 63-96.) Harmful Dust Plants (a) Perform the experiments outlined on pages 64-66. (b) Boil a pint of milk 15 minutes. Pour into bottle which has been boiled in water the same time. Close with cork which has also been boiled. Pasteurize an equal portion (bottle and cork as above). Keep this at about 155 F. for 15 minutes. Keep both under same conditions. Test each day with blue litmus paper. Note first trace of acid. Test by smell and note first signs of coagulation. Compare results in time. When opening, expose as little as possible to dust. Do not lay cork down or touch lower part with fingers. If cork is handled or exposed to more dust, boil again. While cork is out, lay a clean wet cloth over mouth of bottle. References: Dust and Its Dangers, by T. M. Prudden. Chapters VI, VII, VIII. (750., postage 6c.) The Story of Germ Life, by H. W. Conn. Chapters V, VI. (35C., postage 6c.) STUDY PROGRAM 161 Bacteria, Yeasts, and Molds, by H. W. Conn. Chapters XIV, XV. ($1.00, postage roc.) Our Secret Friends and Foes, by Percy F. Frankland, Chapter VI. ($i. 25, postage i2C.) The Story of the Bacteria, by T. M. Prudden. Chapters V-XIII. (750., postage 6c.) MEETING VI (Study pages 96-1 16) Household Applications (a) Make out a list on paper of the most common and most harmful dust gardens occurring in the household the dishcloth, refrigerator, waste-pipe, damp floor- mop, or any cloths put away in dark closets, uncleaned bread boxes, etc. (b) Expose small portions of bread, cheese, sauces, meat, milk to dusty air. Keep in warm, dark places and note time, character, appearance of changes. (c) Consider the care of hands, teeth, all parts of the body; house, sidewalks, backyard, garbage barrels, etc., from bacteriological standpoint. References: Dust and Its Dangers, by T. M. Prudden. Chapters V, IX, XI, XII. ( 75 c., postage 6c.) Bacteria, Yeasts, and Molds, by H. W. Conn. Chapter II, pages 24-31; Chapters VII, XIV. ($1.00, postage ice.) Water and Ice, by T. M. Prudden. (750., postage 6c.) (Select answers to Test Questions on Part II. Report on supplemental work and experiments.) THE BACTERIA SCARE* BY MARY HINMAN ABLE There is a rare form of insanity known to physicians in which the patient is forever washing his hands and fancying that he is polluted by every contact. A few years ago when we were at the beginning of our fight against tuberculosis, typhoid fever and other diseases that may be carried in various forms of filth, it seemed that a mild epidemic of this form of insanity would be a blessing to any community, as it would insure the clean hands which must be insisted on if we are to have clean food. However, when one sees the wholesale and often unwarranted application of a little knowledge of bacteria to every phase of life one is thankful for all the existing sanity and desirous of its extension. For in the wake of every reform is found the trail of the extremist. The Journal of the American Medical Association calls attention in a late issue to certain statements in a book entitled Good Health and How We Won It, by Mr. Upton Sinclair and Mr. Michael Williams. It seems that the writers recovered their health by decreasing the amount of their food and omitting meat entirely. We do not hear as a reason that these gentlemen felt that they were approaching middle life when just this change in the diet has frequently been recommended by physicians, though for reasons unconnected with bacteria; they say they have abandoned eating of meat because of the great numbers of bacteria that it contains, there being, it is claimed, hundreds of millions of bacteria in different cuts of beef steak and several varieties of sausage. * From the Journal of Home Economics. 163 THE BACTERIA SCARE 163 It is said that every form of error may be traced to faulty logic; here the trouble seems to be that the premises are false. "Meat contains many bacteria. All bacteria are harmful, therefore, etc." The inves- tigators do not state the kind of bacteria nor the way they came to be present in the meat, and evidently they believe that meat in and of itself is naturally and normally laden with these minute forms of life. As a matter of fact though results of a different character have been reported not infrequently, care- fully made and carefully controlled laboratory work with all precautions taken has shown that the raw flesh of healthy animals is stirile, and only in certain animal diseases is bacterial life present in the tissues. All living things, both plants and animals, are sub- ject to bacterial diseases, but if bacteria are found on raw or cooked meat from healthy animals it is safe to say that they were lodged there by passing air currents just as they are lodged on any other food thus exposed. Rightly interpreted then, the labora- tory experiments indicate that all foods should be protected from accidental contamination by bacteria, as harmful species may be present among them, not that meat should be excluded from the diet because bacteria happen to be found on it. A very few bacteria, not more than 50 or 60 species, are known to be harmful, many are known to serve a useful function and it is thought that some varieties may even prove to be necessary to the digestive processes. The intestinal tract of man swarms with bacte-.a, and the experimenter has never been able to free from bacteria the digestive tract of an animal that has once lived under normal conditions. Of the foods we eat there are absolutely none free from bacteria, if we except cooked food 164 HOUSEHOLD BACTERIOLOGY fresh from the fire. The purest milk obtainable for the table contains thousands of bacteria to the cubic centimeter, while commercial milk may have many millions. Buttermilk and other forms of acid milk also contain correspondingly large numbers. Many hundreds of these harmless bacteria are known and named, while the harmful or pathogenic bacteria number only a few score. It is these few malevolent microbes that must be avoided, and hence all tha precautions we have adopted as to cleanliness in hospital, market, dairy and kitchen. But if life is to be worth living we must learn where these objection- able varieties come from in order to concentrate at the proper place our use of that eternal vigilance which is the price of health. Here are a few suggestions. Human contact with food is probably the greatest source of danger. If a piece of dry bread fall on the floor of a clean private house the bacteriologist teils us it might be picked up and eaten with impunity. Not so if this bread were to be dropped on the floor of a trolley car, especially in the old days when expectoration was common. The driver's hand which grasps the top of the milk bottle which he delivers may leave bacteria there and the bottle should be washed before the milk is poured out. The diminishing of the number of bacteria in our food by the practice of cleanly habits (and no one of these habits is more important than the thorough washing of the hands before handling and preparing food and before meals) is recommended by all hygien- ists; but there should be no morbid fear of the con- sumption of foods that have been the dependence of the race since the dawn of civilization and before, simply because we do not ordinarily eliminate from them every trace of bacterial life. INDEX Acetic acid, sugar changed to, 61 Acid, butyric, 62 Acids as preservatives, 72 Acquired immunity, 94, 134 Agar for dust gardens, 10 Alcoholic fermentation, 114 Alexines, 93 Animalcules, 109 Antiseptics, 65 Antitoxin, 94, 137-144 diphtheria, 95, 138 Artificial immunity, 94, 136 Bacteria, 16-32 as scavengers, 48 classed as plants, 112 definition of, 16 disease producing, 75 effect of cold on, 90 excretions of, 18 experiments with, 64 food of, 20 forms of, 1 7 growth of, 22 harmful, 63 in cheese making, 60 in coarse meals, 45 in "eyes" of potato, 45 in ice, 85 in milk, 14 in school rooms, 107 liquefying, 74 method of study of, 112 natural home of, 30 nitrifying, 51 on dust particles, 97 secretions of, 31 size of, 23 structure of, 17 useful, 47 with flagella, 27 work of. 47, 54 Bacteriology, history of, 109- H3 lessons for children, 124 Barriers of the body, 129 Bed-making, 102 Blood poisoning, 91 Body, barriers of the, 129 Boiling clothes, necessity for, 3 Bread, baking, 45 * leavened, 6 Breeding ground for germs, 77 Brushing clothing, 106 Burn infected material, 116 Burning sweepings, 104 Butter bacteria, 55 bad flavors in, 58 making, 55 Butyric acid, 62 Canned goods, 70 Carelessness, criminal, 83 Care of discharges in disease, 79 of plumbing, 106 of refrigerator, 29 i66 HO USE ff OLD BA CTERIOL OGY Cause of lockjaw, 80 Cheese, 59 molds in ripening, 59 Cider vinegar, 60 Clean eggs, 73 Clean milk, 14 Cleaning school rooms, 107 Cleanness, sanitary, 108 Clothing, brushing, 106 Colonies of bacteria, 12 of dust plants, 10, 15, 16 Color of mold spores, 38 Common methods of preserv- ing food, 68 Communicable diseases, 75 Compound microscope, no Compressed yeast, 43 Contamination, sewage, 82 Covering food, 104 Criminal carelessness, 83 Crops, rotation of, 53 Cultures, solid, in Deadly dish-cloths, 106 Deaths from lockjaw, 80 Decay, 115 Diphtheria antitoxin, 95 bacillus, 135 Disinfectants, 65 nature's, 98 Disinfectant, sunshine as a, 25 Disinfect soiled articles, 79 Disease, care of discharges in, 79 from molds, 36 germs, 75-86 germs, effect of light on, 83 germs, identifying, 113 germs, origin of, 77 nature of, 131 producing bacteria, 132 Diseases communicable, 75 infections, 133 specific germs of, 76 Drying food, 70 Dust, 1-7 movements of, 4 ordinary, 5, 13 particles, bacteria on, 97 plants, 15 plants in refrigerator 28 plants, life work of, 63 sources of danger, 114 Dusters, washing, 104 Dust-garden out of doors, 73 plot, the, 7 Dust-gardens, 7-14 photographs of, 1,12, 99, !3. 105 planted after sweeping, 98 soil for, 13 Dusting, rules for, 104 time for, 100 Dust-proof room, 2 Effect of antitoxin on the body, 140 of cold on bacteria, 90 of gastric juices on bacteria, 87 of light on disease germs, 83 of poisoning, 92 of sunlight on disease germs, 26 INDEX 167 Eggs, clean, 73 Epidemics of typhoid, 81 Essential oils as preservatives, 72 Excretions of bacteria, 18 Experiences of students, 119- 124 Experiments in hospitals, 100 with bacteria, 64 with dust, 7 with yeasts, 42 Extracts from the Instruct- or's Note Book, 117-125 Favorable conditions for germs, 76 Fermentation, 114 early theory of, no processes, 53 products of, 115 Film-forming bacteria, 22 Filtered water, 85 Filters, porcelain, 84 Fission reproduction, 21 Flagella, bacteria with, 27 Food, covering, 104 of bacteria, 20 Forms of bacteria, 1 7 Formation of pus, 90 Fungi, bacteria classed as, 23 Gas produced by yst, 44 Gastric juices, effect 'on bac- teria, 87 Germ, definition of, 16 Germs, breeding ground ior, 77 disease, 75-86 pathogenic, 66 resistance of body to, 86 Growth of bacteria, 22 of dust-gardens, 1 1 of mold, 33 of yeast, 40 Harmful bacteria, 63 preservatives, 69 Health, definition of, 88 History of bacteriology, 109- "3 Hydrophobia, 148 Ice, 85 Identifying disease germs, 113 Immunity, 92, 134 artificial, 136 natural, 93 Importance of bacteriology, 3 2 Infected material, burning, 1 16 Infection by oysters, 82 method of, 78 sources of, 86 Infectious diseases, 133 Ingredients of dust, 4 Inoculating the soil with bac- teria, 52 Intermittent sterilization, 65, 116 June butter, 55 flavor bacterium, 56 Koch's theory, in Laboratory study of bacteria, 31 Lactic acid, production of, 14 i68 HOUSEHOLD BACTERIOLOGY Leavened bread, 6 Leucocytes, 88 Life, spontaneous generation of, 109 work of dust plants, 63 Liquefying bacteria, 74 Lockjaw, cause of, 80 Making antitoxin, 95 Meadow tea, no Metchnikoff s theory, 93 Meteoric dust, 3 Method of infection, 78 of study of bacteria, 112 Microbe, definition of, 16 Micro-organisms, 16 Microscope, compound, no Mildew, 6, 37 Milk, bacteria in, 14 clean, 14 Pasteurized, 67 souring of, 13 Mold, reproduction of, 33 spores, 35 Molds, 6, 33, 39, 59 in ripening cheese, 59 work of, 36 Moldy houses, 38 Movement of bacteria, 26 Movements of dust, 4 Mustiness, 37 Natural home of bacteria, 30 immunity, 93 Nature of disease, 131 Nature's disinfectants, 96 Necessity of dust, 2 Newman's theory, 93 Nitrifying bacteria, 5 1 Nitrogen traps, 52 Nutrient media for dust-gar- dens, 13 Opposition to vaccination, 147 Ordinary dust, 5, 13 Origin of disease germs, 77 Oxygen, relations of bacteria to, 24 Oysters, infection by, 82 Pasteur's theory, 95 work of, in, 148 Pasteurization, 66, 115 Pasteurized milk, 67 Pathogenic germs, 66 Personal responsibility for sanitation, 108 Petri dish, 7 Phagocytes, 88 Photograph of dust -gardens, i, 12, 99, 103, 105 Planting dust-gardens, 10 Plants, bacteria classed as, 112 Plumbing, care of, 106 Poisoning, blood, 91 effects of, 92 Polluting water, 83 Porcelain filters, 84 Precautions to avoid germ in- fection, 79 Preparing soil for dust-gar- dens, 9 Preservatives, 72 Preserving food, 68 INDEX 169 Prevalence of dust, i Product&fn of lactic acid, 14 Products of fermentation, 115 of yeast growth, 40 Protoplasm, 17 Pus, formation of, 90 Putrefaction, 12 Rabies, 148 Refrigerator, care of, 29 Relations of bacteria to oxy- gen, 24 Removing dust, 104 Reproduction of bacteria, 20 of mold, 33 Resistance of body to germs, 86 of spores, 28 Ripening cheese, 58 Roquefort cheese, 59 Rotation of crops, 53 Rules for dusting, 104 Safeguards of the body against disease, 127-151 Salt as a preservative, 72 Sanitary cleanness, 108 Sanitation, 96-108 personal responsibility for, 108 Scavengers, bacteria as, 48 School rooms, cleaning, 107 Secretions of bacteria, 31 Settling of bacteria and molds, 98 Sewage contamination, 82 Shape of bacteria, 17 Size of bacteria, 23 of yeast, 39 Soil for dust-gardens, 8, 13 Soiled articles, disinfect, 79 Solid cultures, 1 1 1 Source of dust, 3 Sources of infection, 86 Souring of milk, 13 Specific germs of diseases, 76 Spoiling, 71 Spontaneous generation of life, 109 Spores, 116 mold, 35 of bacteria, 27 of yeast, 39 resistance of, 28 Starters, 57 Sterilization, 115 intermittent, 65, 116 Structure of bacteria, 17 of yeast, 39 Sugar as a preservative, 70 changed to acetic acid, 61 Summary, 113 of terms, 114 Sunlight, effect on disease germs., 26 Sunshine as a disinfectant, 25 Sweeping, 97 dust-gardens planted after, 98- Sweepings, burning, 104 Symptoms of poisoning, 92 Temperature for yeast growth , 170 HO USEHOLD BA CTERIOLOGY Terms, summary of, 114 Tetanus, 80 Theories of vital resistance, 88 Time for dusting, 100 Toxins, 93 Typhoid, epidemic of, 81 infection by milk, 81 Useful bacteria, 47 Vaccination, 94, 145 opposition to, 147 Vinegar, 60 Vital resistance, theories of, 87 Wandering cells, 88 Washing dusters, 104 Waste of nitrogen, 51 Water, filtered, 85 polluting of, 83 Work of bacteria, 47-54 of leucocytes, 88 of molds, 36 of Pasteur, 1 1 1 Yeast, 39 compressed, 44 generating carbon dioxide, 43 Yeasts, effect of cold on, 42 experiments with, 42 Zooglea, 22 """PO make housekeeping an inspiring profession, instead of deadening drudgery. nPO make the daily work in the home of fascinating in- terest instead of monotonous labor. nPO make housekeeping easier and simpler by utilizing modern science in the home. ""TO make the household money go further, that the higher things of life may be included. T^O preserve and increase health, and thereby promote happiness and prosperity. '"TO develop the children mentally, morally and physi- cally to their finest possibilities. '"TO effect the conservation and improvement of the American home. ""TO raise ideals of American home-making. American School of Home Economics. NOTE-The 100-page booklet, "The Profession of Home-Making," gives details of the home-study domestic science courses. It's free. Bulletins "The Up-to-Date Home," "Free Hand Cooking" and "Food Values," IOC each. Address-A. S. H. B., 606 W. 69th St., Chicago, 111. THE LIBRARY OF PARTIAL SYNOPSIS Vol. I. THE HOUSE: ITS PLAN, DECORATION AND CARE, by Prof. Isabel Brevier, University of Illinois. Treats of the development of the modern home and the American house, the planning of convenient houses, construction, floors; the problems of decoration and furnishing; gives suggestions for changes, repairs, household conveniences, "The Cost of Building," etc. Vol. II. HOUSEHOLD BACTERIOLOGY, by S. Maria Elliott, Simmons College, Boston. An interesting account of the microscopic forms of life and their relation for good and evil to the household; what dust is and how to make "dust gardens"; disease germs and how to avoid them; the protect- ing agencies of the body and how to keep them active; sanitation, etc. Vol. III. HOUSEHOLD HYGIENE, by S. Maria Elliott, Simmons College. The healthful home; the best situation for the house; importance of the cellar; all about drainage heating, lighting, disposal of wastes, plumbing tests, the water supply; practical suggestions for sanitary furnishings and care; hygenic house- keeping, etc. Vol. IV. CHEMISTRY OF THE HOUSEHOLD, by Margaret E. Dodd, S. B., Mass. Institute of Technology.! "A Day's Chemistry" a fascinating account of the unseen forces in the common things met in a day's work water, air, fire, fuel; chemistry of food, of digestion, of cookery, of baking powder, of cleaning, of laundry, of stains, of lighting; home tests; home-made baking powder, soap, etc., etc. Vol. V. PRINCIPLES OF COOKERY, by Anna Barrows, Columbia University and Chautauqua School of Cookery. "A key to the cook books" analyzing and explaining the principles on which success rests; all approved methods of cookery explained, particular attention being paid to economy of time and materials; full consideration of menus, making a fireless cook-stove, "Directions for Waitresses," etc. Vol. VI. FOOD AND DIETETICS, by Prof. Alice P. Norton, Univer- sity of Chicago. Tells of the composition, nutritive value and digestibility of foods; how the body makes use of food; food economy; the balanced ration; healthful diet for the sedentary, the aged, the children, and so on; food adulterations, etc. HOME ECONOMICS Vol. VII. HOUSEHOLD MANAGEMENT, by Prof. Bertha M. Terrill of Hartford School of Pedagogy. Full treatise on economy in spending; the proper division of in- come; systems of household accounting; system in housework; the servant problem; help by the hour; buying supplies and furnishings; how to market economically; cuts of meat; season of vegetables; ex- periences of students; "Co-operative Housekeeping," etc. Vol. VIII. PERSONAL HYGIENE, by M. LeBos- quet, S. B., Director of A. S. H. E. The wonderful human machine; running the machine; care of the machine sufficient physiol- ogy given to show the reasons for the directions for maintaining health; emphasis placed on do rather than don't; articles on "Ethics of Health," ,'Use and Abuse of Drugs," etc. Vol. IX. HOME CARE OF THE SICK, b> Amy E. Pope, Presbyterian Hospital, New York City. Includes the essentials of trained nursing; specific directions for handling and caring for the patient; nursing in contagious diseases: obstetrics; food for the sick; emergencies; poisons and their antidotes; bandaging; articles on communicable diseases, etc. Vol. X. TEXTILES AND CLOTHING, by Kate H. Watson, formerly Lewis Institute and University of Chicago. Fully illustrated description of primitive and modern methods of manufacture; textile fibres and fabrics; plain and ornamental stitches and their applications; machine sewing; cutting and fitting of waists and skirts, color and ornament; children's clothes; repairs, etc. Vol. XI. STUDY OF CHILD LIFE, by Marion Foster Washburne, editor "Mothers Magazine." Thoroughly sensible and practical direction for the treatment of children; faults and their remedies; character building; home occupa- tions; play; associates; studies and accomplishments; religious training; the sex question, answers to questions, etc. Vol. XII. CARE OF CHILDREN, by Dr. A. C. Cotton, Prof. Chil- dren's Diseases, Rush Medical College, University of Chicago. The care of the baby before birth and of the new baby; healthful clothing; dev-elopment and growth of the child; authoritative and specific directions for feeding; food disorders; food for older children; treatment of children's aliments, hygiene of the child through pubescence, etc L COMMENDATION ON THE COURSE IN BOOK FORM: THE OUTLOOK "It is true that the management of the home and the care of the family may now rightly be called both a business and a profession. Looking at the subject in this light, the volumes of this library may be regarded as the tools and formulae for carrying on the work in a systematized and intelligent manner. ' * A wise discrimination has been exercised in the choice of the authors of the lessons, for these writers are recognized authorities and special students in the various fields with which they deal. In all cases, simplicity of statement and clarity * * * brevity with- out sacrificing completeness, are qualities carefully sought for." THE INDEPENDENT "Each of these series of lessons is written by an expert one possessing special knowledge on the subject concerning which he or she writes. The volumes are handy and are well illustrated and contain an immense amount of in- formation. Things that it must take an old housekeeper years of experience to learn, the young housekeeper may have here under her hand at the very beginning of her regime." GOOD HOUSEKEEPING "Practically all the material needed by the home-maker who wants to know about the inside and the outside of her house and the health of those within it is to be found in these twelve volumes. The books are easy to read and scientific with- out being technical." BOSTON COOKING SCHOOL MAGAZINE "This is the first time that an attempt has been made to gather together the whole broad subject of home economics into one correlated series of volumes. They give an epitome of the kind and scope of instructions given on this subject at the present time." THE CRAFTSMAN "Altogether the course seems to be widely useful in its scope, and very straight- forward and practical in its work." BOSTON TRANSCRIPT "These well printed and liberally illustrated volumes present a course of reading and study that shows to what extent the profession of home-making and art of living make for self -culture and the practical ends of our daily existence." CHICAGO TRIBUNE "Each volume is prepared by practical instructors, speaking with authority in their particular lines. They are well illustrated and are calculated to diffuse a great body of necessary information to those interested in household advancement." IOWA STATE BOARD OF HEALTH BULLETIN "We most heartily commend these courses to all persons interested in healthy homes and the development of a vigorous people mentally, physically and, as a consequence, morally." 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Greenville, Ohio, High School Bureau of Education, Department of the Philippines 40 Sets "Library of Home Economics" The "Library of Home Economics" has been purchased as a reference work by nearly all prominent schools offering courses in home economics or related subjects, by most public libraries of the first class, and by over 4,000 progressive bome-makers. It may be seen at many book dealers. ANNOUNCEMENT "LESSONS IN COOKING, THROUGH THE PREP- ARATION OF MEALS." THIS new correspondence course in cookery has been prepared to meet the needs of home-makers who have had little or no systematic training in modern methods of cooking but who desire to provide for their families sim- ple, yet appetizing and wholesome meals, with the last ex- penditure of time, effort and money. The ordinary cook book, with its numerous and compli- cated recipes, is of little help to the beginner. It does not answer the oft occurring question, "What shall I provide for today, tomorrow, for next week"? It gives no hint of wholesome food combinations or balanced diet. The problem of home cooking is not only how to cook various separate dishes but how to prepare whole meals. The plan of "Lessons in Cooking" is unique and original in that a systematic course in cooking is taught through a series of menus, with detailed directions, not only for cooking the separate dishes, but also for preparing and serving each meal as a whole. The course is divided into twelve parts, in each of which is given the recipes for a week's menu, typical of one month of the year over 250 meals in all. In the first lessons, simple operations - of cooking are described and gradually the more difficult and complicated recipes are in- troduced, leading to advanced work in the later lessons. Throughout the course the question of wholesome food com- binations and balanced meals is carefully considered and special emphasis is given to economy of time and money. All available authorities have been consulted and the assistance of a number of prominent teachers of cookery has been obtained in the preparation of this course, which presents the best modern methods and the latest scientific discoveries relating to the "Fine Art of Cooking." This book is DUE on the last date stamped below JUN 2 1 1933 JAM Form L-9-10m-5,'28 MAL SCHOOL S. CALIFORNIA WWVERSITY of CALIFORNly. AT