CIHM 
 Microfiche 
 Series 
 (Monographs) 
 
 ICIMH 
 
 Collection de 
 microfiches 
 (monographies) 
 
 Canadian Institute for Historical Microraproductions / Institut Canadian da microraproductions historiquas 
 
Technical and Bibliographic Notas/Notas techniques et bibhographiques 
 
 The Institute has attempted to obtain the best 
 original copy available for filming. Features of this 
 copy which may be bibliographically unique, 
 which may alter any of the images In the 
 reproduction, or which may significantly change 
 the usual method of filming, are checked below. 
 
 L'Institut a microfilm* la mailleur eaemplaire 
 qu'il lui a ete possible de se procurer Les details 
 da cet exemplaire qui sont peut-^tre uniques du 
 point de vue bibliographique. qui peuvent modifier 
 une image reproduite. ou qui peuvent eaiger une 
 modification dans la mAthode normale de filmage 
 sont indiquAs ci-dessous. 
 
 D 
 
 Coloured covers/ 
 Couverture de coulaur 
 
 I I Covers damaged/ 
 
 Couverture andommag^e 
 
 j \ Covers restored and/or laminated/ 
 I I Couverture reataurAe et/ou pellicul^e 
 
 □ Cover title missing/ 
 Le titre de couverture manque 
 
 □ Coloured maps/ 
 Cartes gAographiques en coulaur 
 
 D 
 
 71 
 
 Coloured ink (i.e. other than blue or black)/ 
 Encre da couleur (i.e. autre que bleue ou noire) 
 
 □ Coloured plates and/or illustrations/ 
 PIfanches et/ou illustrations en couleur 
 
 f~7l Bou" 
 LlJ Reli* 
 
 Bound with other material/ 
 avec d'autres documants 
 
 Tight binding may causa shadows or distortion 
 along interior margin/ 
 
 Lareliure serree peut causer de I'ombre ou de la 
 distorsion le long de la marge interieure 
 
 Blank leaves added during restoration may 
 appear within the text. Whenever possible, these 
 have been omitted from filming/ 
 II se peut que certaines pages blanches ajoutAes 
 lors dune restauration apparaissent dans le texte. 
 mais. lorsque cela Atait possible, ces pages n'ont 
 pas M fitmAes. 
 
 D 
 
 
 
 n 
 
 n 
 n 
 
 D 
 D 
 D 
 
 n 
 
 Coloured pages/ 
 Pages de couleur 
 
 Pages damaged/ 
 Pages endommagees 
 
 Pages restored and/or laminated/ 
 Pages restaurees et/ou pellicular 
 
 Pages discoloured, stained or fox* ' 
 Pages d^colorees. tachetAes ou pi t i" 
 
 Pages detached/ 
 Pages detachees 
 
 Showthrough/ 
 Transparence 
 
 Quality of print varies/ 
 Qualita inAgale de I'impression 
 
 Includes supplementary material/ 
 Comprend du materiel supplementaire 
 
 Only edition available/ 
 Seule Edition disponible 
 
 Pages wholly or partially obscured by errata 
 slips, tissues, etc . have been refilmed to 
 ensure the best possible image/ 
 Les pages totalement ou partiellement 
 obscurcies par un feuillet d'errata. une pelure. 
 etc.. cnt ite flimies A nouveau de facor a 
 obtenir la meilleure image possible 
 
 n 
 
 Additional comments:/ 
 Commentaires supplementaires 
 
 This item is filmed at the reduction ratio checked below/ 
 
 Ce document est filmA au taux de reduction indiquA ci-dessous. 
 
 10X 14X 18X 22X 
 
 26X 
 
 30X 
 
 / 
 
 12X 
 
 16X 
 
 20X 
 
 24X 
 
 28X 
 
 32X 
 
Th« copy filmed here hes been reproduced thenks 
 to the generosity of: 
 
 Thomas Fithar Rar« Book Library, 
 UnivarsHy of Toronto Library 
 
 L'exempieire film* fut reproduit grice A la 
 ginirosit* de: 
 
 Thomas Fishar Rara Book Library, 
 Univarsity of Toronto Library 
 
 The images appearing here are the best quality 
 possible considering the condition and legibility 
 of the original copy and in keeping with the 
 filming contract specifications. 
 
 Original copies in printed paper covers are filmed 
 beginning with the front coves' and ending on 
 the last page with a printed or illustrated impres- 
 sion, or the back cover when appropriate. All 
 other original copies are filmed beginning on the. 
 first page with a printed or illustrated impres- 
 sion, and ending on the last page with a printed 
 or illustrated impression. 
 
 The last recorded frame on each microfiche 
 shall contain the symbol —^' (meaning "CON- 
 TINUED"), or the symbol V (meaning "END"), 
 whichever applies. 
 
 Les images suivantes ont ttt reproduites avec ie 
 plus grand soin, compte tenu de la condition et 
 de la nettet* de I'exemplaire film*, et en 
 conformity avec les conditions du contrat de 
 filmage. 
 
 Les exemplaires originaux dont la couverture en 
 papier est imprimte sont filmte en commenpant 
 par Ie premier plat et en termlnant solt par la 
 derniire page qui comporte une empreinte 
 d'impression ou d'iilustration, soit par Ie second 
 plat, salon Ie cas. Tous les autres exemplaires 
 originaux sont filmis en commenpant par la 
 premiere page qui comporte une empreinte 
 d'impression ou d'iilustration ct en termlnant par 
 la derniire page qui comporte une telle 
 empreinte. 
 
 Un des symboles suivants apparattra sur la 
 derniire image de cheque microfiche, selon Ie 
 cas: Ie symbole — »> signifie "A SUIVRE". Ie 
 symbole V signifie "FIN". 
 
 Maps, plates, charts, etc.. may be filmed at 
 different reduction ratios. Those too large to be 
 entirely included in one exposure are filmed 
 beginning in the upper left hand corner, left to 
 right and top to bottom, as many frames as 
 required. The following diagrams illustrate the 
 method: 
 
 Les cartes, planches, tableaux, etc.. peuvent Atre 
 filmte i des taux de reduction diff«rents. 
 Lorsque Ie document est trop grand pour Atra 
 reproduit en un seul clich*. ii est film* i partir 
 de i'angle supArieur gauche, de gauche A droite. 
 et de haut en bas. en prenant la nombre 
 d'images nicessaire. Les diagrammes suivants 
 illustrent la mAthode. 
 
 1 
 
 2 
 
 3 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
[XeprinUd from Science, N. S., Vol. XXXIIL, No. 36S, P^u 899-900, June 9, wit] 
 
 STUDIES IN ARTERIOSCLEROSIS 
 
 .. .! 
 
 ■ill 
 
 Mich has appearp<l in the literature in 
 recent years upon the t-tiology and process <if 
 development of arteriosclerosis. Many ob- 
 servations have been made upon the human 
 subject and also in experimental animals, of 
 points co-relating certain factors with the 
 production of diseases in the arterial tree. In 
 most instances these factors have been care- 
 fully studied by competent ob«pr\'ers and in 
 many instances the results have been verified 
 by others. 
 
 The gathering of facts concerning arterio- 
 sclerosis is quite simple— the interpretation 
 of these involves much difficulty. In carrying 
 out any experiment or in offering reasons for 
 a given result, we are constantly reminded of 
 the manifold factors which enter a given ex- 
 periment or which are naturally present. 
 Often our experiment on animals only induces 
 altered conditions which indirectly bring 
 about the result we are seeking. That the 
 greatest care must be exe*ci.sed in drawing 
 inferences from animal experimentation is 
 well illustrated in studies upon arteriosclerosis. 
 Kecently I^' in and Larkin" have published 
 the results of their experiments on dogs, in 
 which by producing an arterio-venous anasto- 
 mosis between the external jugular vein and 
 the external carotid artery, they arrive at the 
 sweeping conclusion that " arteriosclerosis can 
 not be artificially induced in a previously 
 healthy blood-vessel by u change in the blood 
 pressure alone." To this ti/pe of conclusion 
 we must take xception. 
 
 Levin and arkin, experimenting on ten 
 •logs, joined th< external carotid artery to the 
 •Jour. Krprr. Med.. 1911. XIFI., p. L'4. 
 
 external jugular vein. In two of these <U.g^ 
 thrombosis occurred close to the line of suture 
 in the vessels. All but two of the remaining 
 eight animals received injections of adrenalin 
 at varying periods. These eight dogs, whioh 
 form the positive results and from which the 
 above positive statement respecting arterio- 
 sclerosis was made, were allowed to live Wi. 
 •■?8, 72, 1,'j, 124 and 58 and 44 days, respectively. 
 Xo one, who has studied diverse patho! ,^- 
 ieal lesions, will deny that the distribution .f 
 various lesions in organs is not unifrrm u 
 the animal world. Man is particularly siih 
 ject to lesions of the circulatory system- .i 
 condition not so frequent in lower animal-. 
 Rabbits and horses occasionally suffer froTii 
 arterial lesions — more often seen in the oMei 
 animals and in certain breeds. Dogs and '>!U- 
 rarely develop lesions in the arteries, even 
 under the most trying ircumstances. 
 
 This varying susceptibility still awaits an 
 explanation, but in the face of our ignorane. 
 in the matter, we must assume the gre.ate-t 
 care iu drawing broad conclusions or in pro- 
 posing far reaching principles. Negative e.\- 
 perimental results for the dog have no positive 
 bearing upon experimental facts observed in 
 other animals. 
 
 Much criticism is offered against the use nt 
 the rabbit for experiments upon the circuLi 
 tory s.vstem. The comment has been that 
 spontaneous arterial disease occurs in thi- 
 animal. And yet none of the critics offer any 
 suggestion for the cause of this spontaneou- 
 lesion! Properly seleete.1 animals and con 
 trolled experiments eiui reduce the error <•( 
 
SCIENCE 
 
 2 
 
 ■ spontaneous " disease to almost a vanishing 
 point. The Tery feature, in the rabbit, of 
 n ailil.v reactinjr in its nrtrrial tree to different 
 iioxiP, determines its usefulness for studyinp 
 t\v diseases of the circulation. 
 
 In the experiments of the above-citwl au- 
 tliTs. the observations were made upon the 
 Miious segments of the anastomosis. Here 
 although in only some of the animals the vein 
 ttiii noted to be dilated, it is concluded that an 
 increased blood pressure existed in all. It is 
 not at all clear to what extent the blood pres- 
 sure was increased when the external carotid 
 and external jugular were united. With the 
 fae anastomosis which exists (varying much 
 ill individual animals), between the venous 
 iliannels of the neck, it is possible that an 
 increase of pressure exists for only a short 
 |.. riod after the successful anastomosis.' 
 
 -.See Carrel and Guthrie, "Surg. Oynac. and 
 (iLstet.," 1906, Vol. II.; and Watts, Bull. Johim 
 lluidins Hosi)., 1907, Vol. XVIII. 
 
 It is further to be pointed out that various 
 observers have ret-orded that periodic and in- 
 termittently increased hi 1 pressures have 
 
 <iuite i» ditTercnt effect iiiM)n the idood vessels 
 than a constant and continuous one. The 
 [leriotlically increased pressure is found com- 
 monly in man, and if we may draw any con- 
 clusions from the finding of occupation scler- 
 osis (right radial sclerosis in the blacksmith, 
 femoral sclerosis in the policeman), it is that 
 the peritxlic increase of pressure leads to de- 
 generations and sclerosis in the arteries. 
 
 Finally, but of primary importance, the 
 results of observations on veins can not be 
 utilized in drawing conclusions aliout arteries, 
 as has been done by Levin and Larkin. 
 
 Oscar Klotz 
 
 University or Pittsbuboh, 
 February, 1911 
 
 I'