IMAGE EVALUATION TEST TARGET (MT-3) ^/ .^* >•>' ^. M 91 Photographic Sciences Corporation S ■^ JV <^- \ c\ - od, to the extractive sub- stances, and to the potassium .ialts ; cerebral (edema and urfiemia ; the internal secretion of the kidney and unemia ; experimental unemia from double nephrectomy and its relation to human ob- structive uraemia, and other types of human unemia. A question of fundamental importance in the patholoory of urfemia is whether the blood in this condition is more toxic when introduced into the circulation of animals than is human blood from normal person.s. In the hope of answering this (juestion, the blood serum from 28 untimic ))atients, who were I)led during life, was introduced intravenously into rabbits, proper precautions being taken as regax'ds the freshness of tbi' serum, its temperature, the rate of infusion, the exclusion of air from the vein, etc. The observations were not confined to rabbits, but included in some instances dogs and monkeys. Two different methods of intravenous infusion were employed. In one case the serum was infused into the femoral vein at a fixed rate until the com- mencement of fatal symptoms. In the other case, the serum w^as injected in much smaller amount, either into the femoral vein or into an ear vein with a view to ascertaining the minimum dose capable of causing death in the course of 24 or 3C lOurs. A difficulty which at once confronts the investigator in the use of these methods is the fact that normal human serum is in itself toxic to rabbHs in a considerable degree, owing chietfy perhaps to its power of inducing coagulation. Thus I have found that its re(|uires from 25 — 40 c.c. of normal human serum to the kilo to initiate fatal symptoms in rabbits when the inethod of continuous infusion is employed, while it .seems generally agreed among investigators that the fatal dose of human serum, as employed by the second method, is from 9 — 12 c c. per kilo. Inas- much as it is found that there is considerable variation in the toxicity of the same serum for different rabbits of the same weight, notwithstanding every precaution in making the infusion, it is clear that it is necessary to observe much care in concluding that a given class of serums is more than normall}'^ toxic.'' Of the ursemic serums which were studied with respect to their ' The details of the experimental observations will be elsewhere published. - Uhlenhuth claims that the serum should be subcutaneously injected into fjuinea pigs to avoid the error incidental to intravenous infusions. In several instances where I have employed this method, there seems to be no doubt that the blood wan more than normally toxic, judging? from the standard of normal toxicity given by UhleJihuth. 8 toxicity, 19 were obtained from cases of urminia characterized by the occurrence of well marked and repeated convulsive seizures/ six of these being instances of puerperal eclampsia. In the nine remaining? cases the serum was obtained from patients with chronic nephritis, characterized by dyspntm and 'ligh tension pulse— none of these patients having had convulsive seizures. The inferences which we may make from the study of these serums are as follows : The cases of nephritis characterized by dyspncea and high tension pulse without convulsions, taken as a class, do not yield positive indications that the toxicity of the serum was greater than normal, although in at least two of the nine cases the toxicity was considerably greater than any I have observed in health. On the ether hand the least toxic of these serums possess toxic values that come so near the highest toxic values observed in normal ^ >rums that we cannot be certain that they are quite normal. More observations are required before a final judg- ment can be formed regarding these cases. Taken as a class, the serums from the convulsive group of uraemias show a degree of toxicity distinctly greater than any which I have observed for normal serums, and although there are a few of the 19 cases in which the results are difficult to interpret, there .seems to l»e no d(jubfc that im increa.se in the toxic properties of the blood is a characteristic of cases of convulsive urasmia. This latter statement apparently holds good also of certain serums from patients with puerperal eclampsia, but here again more observations are re(|uired. Volhardt has quite recently denied that there is any increa.se in the toxic properties of the blood of eclamptic patients, but his results cannot be regarded as final. Admitting that the serum in convulsive uraemia is more toxic than normal .serum, the question at once arises, what is the cause of this pathological increase ? It is not possible at present to give a satisfactory answer to this question, but the following facts bear upon it. In the first place the toxicity of uraemic serum for animals is greatly reduced l)y exposure to moderate heat, say 60°C. for a few minutes. This is also true of the toxic properties of normal human serum. These facts suggest that the increased toxicity of ursemic blood is dependent on the presence of an increased amount of a toxic proteid substance which is normally present in the blood.' We cannot, however, feel certain that the increased toxicity of the serum does not depend on some ' In one of these cases there were merely coarse twitchings never amouiitinp; to typical convulsions. * The toxic properties of urea, extractives, salts, etc., are of course not influenced by so moderate an elevation of temperature. unknown foreign substnnco. A fact wliicli strengthens tlie view tliat a proteid suhstanee is responsible for the toxicity of unemic, as of normal serum, is that the removal of the proteids hy means of absolute alcohol almost wholly deprives the serum of toxic pi-operties. In trying to form an estimate of the significnnee of an increase in the toxic properties of uranuic as conLrasted with normal serums, it is important to i-(!Cogni/e that such an inci'ease in toxicity does not con- stitute proof that the cause (jf this augmented toxicity is the caus(! of the obtrusive cerebral symptoms of uriemia. It is conceivable that alterations may occur in tlie blood which possess little pathological signilicance for the human organism, but which are nevertheloss capable of rend(>ring the scrum more toxic than normal when intro- duced into the circulation of rabbits This does not, however, seem a probable explanation of the phenomenon of augmented serum toxicity, and is especially at variance with the fact that unv ur.'emic serums hav, in some instances, exhibited very striking toxic properties when introduced into dogs and monkeys, which do not possess the peculiar susc(!ptibility to normal human serum that is observed in the case ol rabbits. It is much more rational to regard the increase in the toxic properties of the blood in certain, if not in all, cases of unemia as evidence of a toxaemia, which is in some way connected with the symptoms of the uraemic state. It is possible that this toxaemia is distinctive of uni^mia and always of the same character, l)ut there are certain dift'erences in the beha\i()ur of different serums which make it likely that the toxjiemia is not always the same. It is, moreover, certain that the toxic properties of the blood are augmented in con- ditions not uraemic in nature, for example, in acute lobar pneumonia, in scarlet fever, etc. Urea being by far the largest and most important constituent of the urine and representing the terminal product of proteid metabolism, it is not singular that this substance should have been for a long time regarded as the main factor in the production of unemia. It is thus of the highest importance to vletermine the actual relation of urea to uriemic states. The conclusion^ reached by me in reference to this relation are based upon a considerable number of determinations of urtsa in the blood of unemic persons, of persons with other pathologi- cal conditions than unemia, and of entiriily normal persons. Many of these observations were made upon blood drawn during life, but these were supplemented by others upon post-mortem blood, after it was demonstrated both in man and in animals that the urea content of ante- and post-mortem blood corresponds closely in the case of blood taken from well preserved bodies. In addition to. making seventy observation.^ on the urea of human blood, an endeavour was made to dotenniiio to vvliat extent chemically pure urea possesses toxic proper- ties. The results of these studies may be brieHy stated as follows : (a) In a small proportion of typical cases of urnnnia, characterized by the occurrence of convulsions, the urea content of the blood was found t(j be well within the normal limits, notwithstanding that in these same cases the blood serum was distinctly more toxic than normal. It is plain that in these cases there is no fjrround for lookin<;j with suspicion upon urea as a factor in pnxlucing symptoms. (h) In the majority of cases of uraimia, esi)ecially in those cases in which the .secretion of urhie has for a long time been .scanty, tlie urea of the blood was distinctly iucreased, this increa.se sometimes reaching to 5 or 10 or even 20 times the normal urea content. It is, however, a very .striking fact that many ca.ses oi' chrcmic nephritis were found to be characterized by a markedly exce.ssive urea cont(Mit, even where there were no symptoms that would ordinarily be called unomic. Tiiis is merely a continuation of an old ol)servation by Bright and Christi- son which has not received the attention which it de.serves. Among the cases in which the urea was increased in the absence of typical unemic symptoms were 14 cases of acute lobar pneumonia with fatal termination. These cases make it clear that renal inadeijuacy is a feature of many fatal pneumonias. Whether such inadecpiaey is to be considered unemic in the absence of the usual sym})toms of urjBmia will be considered later. (c) Experimental .studies upon dogs and monkeys show that pure urea is toxic when infused intravenously, but only when very large quantities are employed, i.e., (juantities e(|ual to many times the daily urea excretion of the animal. The .sym])toms produced by such in- fusions are fairly constant in dogs, and consist in initial slower and stronger heart action, copious diuresis, diarrhd'a, contraction of the pupils, irregular fibrillary contractions of the nm.scles, and finally general and severe tonic or clonic spasms and death. If we make the bold assumption that in human nephritis the su.sceptibility of the nervous .system to the influence of urea is similar to that observed in dogs, we would expect convulsive seizures to arise in man when the urea content of the blood reaches about .o per cent. It was found however, that in many of the cases of human nephritis, in which con- vulsions occurred, the percentage of urea was considerably below this point, while in a few cases in which this percentage was much ex- ceeded, convulsions were ab.sent. It is, of course, obvious from the foregoing facts that urea does not play a necessary part in the causation of the .symptoms of human 6 convulsive uraemia. This does not, however, prove that the accninu- lationof the ureain tlieblood in hirge excess is of little importance. There is good evidence that such an accumulation points to a consider able degree of degeneration of the; .secreting (•|)ithelium, and the degeneration which permits the .storage of una, permits the storage of other constituents of the blood, including sodium chloride, potassium salts, nitrogenous extractives, and po,ssil.ly a toxic proteid substance. It is partly on account of this multiplicity of substances retained in the l)lood at tlie same time with urea that we are unable to fix more definitely on the part which urea plays as a toxic .substance. It is on the whole very likely that urea in conjunctiim with the accuiindation of other substances in the blood, as the result of renal insufficiency, exerts an influence in the production of uraemic symptoms— es))ecially ursemic vomiting and diarrho'a. The urea of the blood has been greatly increased in all the instances of unemic vomituig and diarrhoea that I have had an opportunity to study. It is desirable to indicate here that the customary detenninaticn of urea in the urine in cases of nephritis gives no more indication of the quantity of urea in the bloo, and this fact has led some ph} siologists to snspt.'ct that the high.y toxic ammonium carbamate mf^y be responsible i\n- uiiemic states, '.riiis view appears to mo to be at variance with the following facts: 1. In wuterv b^>lu.''>n ammonium carbamate is very unstable and is i-apidly converted into a.nmonium .carbonate. We know, however, that ammonium carbcmate does not occur in urannic blood in sufficient amount to produce .symptoms, and usually cannot be found at all. 2. The toxicity of uremic blood is not le.s.sened by dialysis, as it wouhl be if the toxicity depended on a difl'u.sible amuKmium salt; nor does the ditt'usate contain ammonium. a The uri le of uraiinic patients docs not necessarily contain an in- creased proportion of N. of ammonia, as it should do if the synthesis of urea were impaired. On the other hand, in liver diseases in which there is extensive pav.'nchymatous destruction, the N. of annnonia may be greatly increased, even in the absence of urtemic symptom.s. Owing to the instability of ammonium carbamate its isolation from the blood is impracticable, and inferences as to its occurrence there depend chiefly on indirect^ evidence. The conclusion seems justified that such knowledge as we possess does not support the supposition that ammonium carbamate is concerned with the production of uremic intoxications. Before passing to the more constructive consideration of the uroemic problem, it is proper to make brief reference to two widely diiferent theories of th>' nature of ura^uia. One of these is the celebrated hypothesis of Tr»yube that renal disease causes thinning of the blood plasma, hypertrophy of tin; left ventricle and excessive arterial pres- sure. Jf the arterial tension is increased beyond a certain point or the plasma of the blood becomes further thinned, (rdema and anaamia of the brain are i)ro injection of kidney extract into the circulation of a nephrectomized dog cau.ses the temporary disappearance of uneuiic phenomena. The evidence which has been advanced to establish this fact must be regarded as insufficient. Thus the observation of Brown-Setjuard that the injection of kidney extract causes an increase in the muscular power of nephrectomized dogs, rests on a small number of experinx-uts which appear neither to have yielded decided results nor to have been subjected to careful control, and Meyer's contention that the injection of renal extract gives marked relief to the dyspnor^a of double nephrec- tomy likewise rests on a small number of observations that .seem distinctly to call for proper controls. Nor can we place much reliance on the claims of Teissier and Frenkel, in a recent publication, that the injection of a ^e\v cubic centimeters of renal extract in the human urrernic sulyect is ciipable of rendering a hypotoxic urine hypertoxic by stimulating the elimination of to.xines through the urine at tin; .same time that the symptoms of uraMuia are ameliorated. Consider- ' These cliaiige.s are not by any means (list incfive of ura'inia, but occur in a variety of condition.s. According to Dr. James Ewing they are best seen where the nerve elements have been subjected to pressure, as in cerebral hemorrhage. 10 al)le peivsonal expei'lence makes ine liighly skeptical as to the propriety of our (1) awing inferences as to the condition of the blood from the effects of intravenous infusions of urine in animals. A very obvious and serious gap in the experiments of Teissier and Frenkel is the absence of observations on the toxic salts ingested with the food and eliminated with the urine, the toxicity of the urine, both in health and disease, being largely dependent on its potassium salts. Future investigations may sliow that the kidney elaborates an internal secretion, but at pi-esent we are justitied in taking the position that the observations now i-elating to this question do not help us in ex- plaining the pathology of uraemia. Passing now to a consideration of the clinical types of uraemia with a view to the discu.ssion of their pathology, it is desirable first to make reference to the phenomena of double nephrectomy in dogs and their relation to human uraemia of obstructive origin. The alteration ? in the composition of the blood that are entailed Viy doultle nephrectomy are of the greatest interest in the study of the pathology of ui'annia, foi- tlu'V necessarily represent the results of the mo.st extreme degree; of renal incompetency per se and without com- plicating factors such as are commonly present in human uraemia. The following description of the symptoms and pathological altera- tions incidental to experimental urjiemia, is based on a series of 10 successful cases in dogs, as well as on cases in the pig and rabbit — anYi::g the operation, of repeated vomiting sometimes associated with diarriiwa, of slow and deep respiration, of slow, full and high tension pulse and, not rarely, of fibrillary twitch- ings. In only one instance did true convulsive seizures occur. Death is usually preceded by a period of drowsiness or actual coma. In none of my animals was the operation survived more than four and a half days, and most of them lived less than three days. In cases unaccompanied by infection the temperature is generally one or two degrees below normal for one or two days before death. A considerable number of observations have been made by me to determine whether the blixxl of nephrcctomized dogs is more toxic to rabbits than the blood of normal dogs; or, to put it a little differently, < The vomiting rufuruble to the removal of the kidneys must be distinguishable from that which results from peritonitis accompanying accidental infection in these c ises. r« 11 to determine whether the experimental uraemia of double nephrectomy is comparable with human uruitnia of the convulsive typu as regards the toxicity' of the blood. There can be little doubt that this is a most important (juestion in tlie pathology of ursemia, and I regret that it is not possible for me to make an unqualified statement in regard to it. Owing to the crudeness of ou'' methods of studying the toxic properties of the blood, it is not possible to detect moderate deviations from the normal toxicity. It can, therefore, only be said that thei-e does not seem to be a marked difi'erence in the toxic properties of the blood within 4S hours after nephrectomy as com- pared with the blood of the same animal previous to nephrectomy, but that the toxicity of the blood seems to be increased in dogs that live a longer period. As regards the changes in the chemical composition of the blood, our information is much more positive. We know, for example, that the urea of the blood is remarkably increased after double nephrectomy — often reaching ten times the normal percentage at the end of three days. The extractives are also distinctly increased. A moder- ate increase in the total .salts of the blood is pi'obably a regular feature of the blood of nephrectomized animals. The potassium salts may be somewhat increased, but on the other hand may not be appreciably changed. Tho total proteids undergo no alteration in amount. A very interesting feature of the blood has been the marked increase in fibrin which was noted in a number of the nephrectomized dogs. This observation, though one of much interest if confirmed, has not yet been subjected to the controls which are necessary to establish it as a fact, for a very definite source of error remains to be eliminated. This consists in the fact that a part of the increase in fibrin noted after nephrectomy may be due to the bleeding which was practised several days before nephrectomy for the purpose of establishing a basis of comparison before and after operation, for it is known that the fibrin of the blood is increased l>y bleeding.' In order to be able to compare the symptoms of double nephrec- tomy with the obstructive type of human uraemia, the cases of ' Since this paper was read I have succeeded in several instances in performing double neplirectoraies and ureter ligations without losing more man a few c.c. of l>lood, through hemorrhage. All these animals have shown a doubling of the normal fibrin content of the blood after a few days. A dog subjected to laparotomy without nephrectomy, but with a moderate loss of blood, showed no increase m the llbrin content of the blood. These observations seem of especial interest in connection with the altered toxicity of the blood after nephrectomy, but other sources of error remain to be eliminated before the increase in fibrin can be positively attributed solely to the sup- pression of renal functions. 12 prolonged anui-iii I'roiii oKstructioii access iltlo in literature we're subjected to analysis. Of the 41 ai)i)arently reliable cases in which anuria lasted four days, .S.j t)ccurred in males. This sti-iking dilfer- ence in sexual iii3ideiice is prol)al)ly explained i)y the nature of the obstruction to the escape of urine. In 14 of the 21 cases in which an autopsy was made the uret(M- or pelvis of the kidney was obstru(-t(Ml by a calculus, on one or both sides, tin; obstruction tluis ci'eated bein^'' the cause of the anuria. I have been unable to find the record of i case in which anuria in a f(;male was due to obstructior. of the ureter or pelvis by a calculus. Of 30 cases in which there was either absolute anuria (if we can trust the hi.stories) or in which only an insignificant (juantity of uriiK! was passed, the condition in 1 1 cases last. 'd nioiv tiian 4 days and less than 7, in IS cases lasted from 7 to 14 days, and in 7 cases lasted longer than 14 days. Although the records are not wholly satisfactory, they serve tu bring out clearly some important facts ]-egaiding the symptoms of ob- structive uricmia. It is interesting to note that in seven of our forty- one cases it is delinitely stated that no uriemic symptoms occuri-eil, although some of the cases were of con.siderable duration (5, 5, (1, 7,S, 9 and 11 days). Although it is not unlikely that some of the unob- ti'usive indications of ura-mia were overlooked in these cases, it is fair to supptjse that there were no well-marked ursemic symptoms. It seems clear that it is the rule for uriemic symptoms not to begin for several days after the connnencement of the anuria. In a number of cases more than a week elapsed before pronounced indications of ui-semia began. In twelve of the forty-one cases it is noted that vomiting was present at some period of the anuria. In one case (that of Russell, lasting twenty patlioloj^'ical conception docii lot explain. We mnst, however, renunnber that in the one case we have to do with an acute condition arisin<^ .sometimes in persons whose vascular system is Jiot n'.nrk>.^d!y altored, while in the .second ca.s<. tlie toxtemia is a chronic state arising hi. a person who, simul- taneously, and for reasons not understood, has developed curdio- vasculai- librosis. It is possible that this cardio-vascular fibrosis plays a mechanical part in the production of dyspntua in the presence of a urfBinic toxiemia like that referred to. In the course of the arterio-sclerotic type of chronic nephritis, with unuinic dy.^^pncea, etc., as well as in other types of nephritis, <;a.stro- enteric disturliances, espucii'.Uy nausea, vomitin\.t\\n- In.neal element in the forms of urfemia already considered is the presence of the i)roteid serum poison to which retcrence has Iteen made; although in the form of uraunia characterized hy <,'astro-enteric deranfji'ments, the accumulation of urea, salts, etc., appears to lie a rr-^nilar and prohahly a diitermininj,^ fact(a-. An element (piite dilferent from simple renal insufficiency enters into Jiiany cases of uneniia, namely that of infection. There is a small hut su-i';:jestive group of patients who, after ex- posure to cold or wet, develo]) high fever, partial suppression of urine, alhuminuria and perhaps luematuria, with headache, delirium and coma. The pecuHarity of the.se cases is that the kidneys have pre- viously been normal so far as can he determined hy clinical methotls. There seems little douht that the cen-hral symptoms in such cases of acute degeneration of the kidney or acute exudative nephritis are due wholly to the action of toxines and not to the retention of sul)- stances in the Mood which are normally eliminated hy the kidney. These unusual hut instructive cases ajjpear to me to n^present the tvpe of ui-a'mia most widely removed from human obstructive urnMuia in its pathological basis. As might l)e expected, these cases retain their purely infective type oidy a short time, for the dnmage to the kidney soon leads to prou(nniced insufficiency and to the accunuilation of urea; extractives, etc., in the blood in marked exoral .' . luptoms such as delirium, coma or convulsions. At autopsy the kidney may show the lesions of an acute nephritis grafted upon those of a chronic nephritis. Post-mortem cultures made fiom the blood and various organs frcMpiently show the presence of pyogenic or other iKithoo-enic bacteria. In short we have in these cases both clinical and pathological evidence of the occurrence of an acute infection. It seems reasonable to suppose that many of the symi)toms which we call ursemic in these terminal cases arc due to the comljination of this infection with a pre-existing toxtemia due to chronic renal insuffi- 1 Tlie increase in the fibrin content of tlie blood wliicli I liave found in some cases of tliis sort is of interest in this connection, though its signillcance is still un- certain. 18 ctoncy. But such infections are by no means always terminal states. It lias heoji shown hy Welch and others that patiei with chronic nephritis are especially susceptil)le to infection, and it often happens that a patient with chronic ditluse nephritis develops ^rave cerebral symptoms at the time of a trivial infection which causes a tonsilitis, rt sli^'ht bronchitis or an otitis, — symptoms which wo very properlv look upon as urjemic, but from which tlu-n^ is apparently complete j'ecovery. Reference has already been made to the fact that the urea content of the blood was found to be almost re<^ularly incrt;as"d in persons dying of acute lobar pneumonia, in other words, that renal insutti- ciency for urea is > characteristic of fatal pneumonias. This observa- tion suggests the (juestion whether we are to regi.id a markedly ex- cessive accumulation of urea in the blood as an indication of uraemia even in the absence of typical clinical indications of urionua. I strongly incline to the view tliat we should extend our conception of the term uramiia to include every case of renal insuHiciency for urea although well deHncil unemic symptoms lie wanting. It has l)een made clear that typical unemic symptoms may arise in persons whose lilood shows no inci'case in urea, but this fact does not deprive the accumulation of urea, salts, etc., of clinical signiKcance ; it merely illustrates that the pathrjlcgical basis of what is clinically termed urseinia i^ not always the same. It seems to me desiraiile that we should regard any toxsem^a as urremic which can Ite shown to depend on the incapacity of the kidney to perform the functions of a healthy kidney, whether these functions consist simply in the elimina- tion of substances as they exist in the blood furnished by the renal artery, or whether they shall be shown also to consist in the trans- formation of certain elements of the blood previous to elimination. Again it is only rational that we should recognize that the essential elements of a urfemic intoxication may exist without lieing present in such a degree as to cause obtrusive and typical uraemic symptoms. Or, to restate the fact in a ditterent form, )i:e Nhoidd recognize that there is such n thing tin n latent itra'.niic intoxication. Such a latent uraemia is probably present in many forms of disease, especially acute flisease, such as pneumonia, where the kidney is the seat of lesions, aud in chronic nephritis. In the former condition it constitutes a complicating state. The fact that such a toxaemia may be masked by associated condi- tions or may be in itself unrecognizable clinically does not prove that it is a state which exerts no influence in determining prognosis. In conclusion a word must be said about the most obscure type of 19 nrnpinia — puprporal c'claiDpsin. Ktlurts have heen made to connect this state with the formation of toxic pnxhicts fonncfl hy thf ehemioil activities of the livin;,' cells of the emltryo, with the ahsorptioii nf toxic material ff)i'meil in the inti'stine anil with the accnmulntion of urea in tin* ItliMid as the result of ne|»hritis or of ))rt sure on the renal vessels, hut the efficacy of these supposiid aj^encies still remains unproved. My personal experience with puerperal eclampsia is limited to the study of the lilood of six victims of this state.' In at least three of these cases the in'ea of the hlood was not increased in perrrnta;^!.. |t, seems hi;^hly prolialtle that the toxicity of the Mood was distinctly in crea.sed in at least two of these ca.ses. Of the other ca.ses it cannot he positively stated that the hlood was more toxic to animals than is ever the case with the hlood of non-eclamptic puerperal women, nor, on the other liand, can it !>(> stated that the l)l()od was not more toxic than normal. At the present time there is a controversy as to the toxicity of the lilood of eclamptic women, which can V»e definitely settled only hy ntunerous and very carefully conducted observations. Although there is thus consideiable uncertainty as to whether an increased toxicity of the hlood is an essential feature of puerpeial eclampsia there is im- portant indirect evidence of the existence of such a to-jivmia. This consists in the presence of ansemic and heinoirhayie airas of necrosis in the livers of women dying of eclampsia." Schmorl, who first described these striking lesions, i-egards the thromboses of the capillaries and small periportal veins with vdiich they arc associated as dependent on the passage into the blood of |)Iac*;ntal elements and products of jtlacental degeneration Flexner has succeeded in producing similar alterations in th" liver l)y means of experimental intoxications, and there caii Ije little doubt that we must regard the necrotic changes in the c ms of (^chimptic women as dependent on a toxa'mia. How this to: .uia a"'«es and how it is related to the toxaemias of nephritis already ....scus3ed remains to be discovered. Although this sketch of the pathology of unwmic condition."-', made from a somewhat personal standpoint, shows us to be in possession of a miiagre fund of knowledge respecting the pathological basis of ura3mia, we may confidently hope for furth.er enlightenment from experimental pathology. It seems to me that future researches should have refer- 1 The blood from these patients was obtained throut;!! the courtesy of the attend- ing pliysicians of the Lying-in Hospital of New York. 2 I have never met with these lesions in the livers of persons dying from other forms of unemia than puerperal eclampsia. 20 ence especially to the following topics : The toxic properties of the hlood of uraemic patients, the physiological and chemical changes induced in the blood by nephrectomy, and the influence of intoxications of intestinal origin upon the normal organism and upon organisms which are the seat of nephritis. That the state of bacterial activity in the intestine is capable of exerting an important influence upon uraemic conditions is suggested by the observation which I have made that the albuminuria of a dog with chronic nephritis can be strikingly increased by feeding with cultures from the stools of entero-cohtis It is also suggested by the exacerbation of symptoms which we some- titnes observe clinically in human patients after gross errors in diet.' This relation deserves further attention, as it is of the utmost practical importance in chronic uraBuiias. I had hoped to refer this evening to methods of treatment in uraemia, but am conscious of having already overstepped the limit of time imposed by reasonable usage. ' Nephritis and uraetnia may also arise in children as a consequence of intense enterocolitis,