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SCIENCE 



[N. S. Vol. XLIV. No. 1132 



tion of the importance of the lower animals 

 in relation to human disease. The subject 

 is a vast one and may be discussed from 

 many standpoints. Medically, animals 

 may serve humanity or they may be di- 

 rectly responsible for terrible scourges. 

 For experimental and teaching purposes in 

 all departments of medicine they are indis- 

 pensable and this forms one great field of 

 usefulness for them. A second field is 

 their use in the production of curative sub- 

 stances — serums, vaccines, ductless gland 

 preparations, drugs, etc., a field which 

 marks an epoch in modern medicine. 



The relation of the lower animals to the 

 transmission and causation of disease is 

 another phase of this subject, but here the 

 results, unlike those in the two fields above 

 noted, are almost invariably serious for the 

 welfare of man. In this field many great 

 and interesting discoveries in recent years 

 have been made. I shall limit myself to 

 this topic and shall try to point out some 

 of the more noteworthy features in this re- 

 lationship and their bearing on preventive 

 medicine. 



Historically, in the very earliest accounts 

 of primitive people, there are records con- 

 cerning the relation of animals and animal 

 parasites to the causation of disease. In 

 Hirsch's classical work on geographical 

 pathology we find a discussion of the rec- 

 ords of the "fiery serpents" (probably the 

 guinea-worms) that afflicted the Hebrews 

 in their wanderings in the desert ; and Plu- 

 tarch narrates that "the dwellers by the 

 Red Sea suffer from a serious malady due to 

 a small serpent which issues from the skin 

 to gnaw the arms and legs and retires un- 

 derneath the skin if disturbed, causing the 

 patient intolerable pain. ' ' Intestinal worms 

 especially were well known to the ancients 

 and form an important chapter in their 

 medicine. In primitive peoples bites and 

 lacerations by wild animals and snakes 

 with the resulting secondary infections fol- 



lowing such wounds gave rise to disease. 

 Rabies was known over 2,000 years ago. It 

 is of such a nature that its relation to dogs 

 and other animals could easily be traced 

 and this connection was well appreciated 

 by the medical authorities in those times. 

 Varro (116-27 b.c.) suggested that malar- 

 ial fevers were transmitted by insects. 



A landmark in the relationship of ani- 

 mal and human disease was the observa- 

 tions of Jenner in 1796 on the relation of 

 smallpox and cowpox. The story is well 

 known and need not be related here. It is 

 a splendid example of careful observation, 

 experiment and practical application even 

 for our own day. Many of our most im- 

 portant modern problems — infection, im- 

 munity, prophylaxis, anaphylaxis, vacci- 

 nation — have their beginnings here. 



Coming now to the bacteriological era in- 

 augurated by Pasteur during the latter 

 part of the last century we note that the 

 connection and interdependence between 

 many animal and human diseases, though 

 recognized before, became ever clearer and 

 more definite. The work of Pasteur on 

 animal diseases, especially anthrax and 

 rabies, of Villemin on tuberculosis, of Koch 

 on anthrax and tuberculosis, of Loeffler on 

 glanders, of Bollenger on actinomycosis, 

 may be mentioned in this connection. This 

 was the era of great and numerous discov- 

 eries and the principles then established 

 have directed and stimulated bacteriologic 

 work to the present day. 



Shortly after the advent of the bacterio- 

 logical era there was superimposed upon 

 this another era, that of protozoology. 

 This may with propriety date from the dis- 

 covery by Theobald Smith in 1889 of the 

 causal organism (Piroplasma bovis) of 

 Texas fever in cattle. A little later Smith 

 and Kilbourne determined that the mode 

 of transmission in this disease was by the 

 cattle tick. The fact should be noted how- 

 ever that many years before, in 1864, Pas- 



