ZOOLOGY AND MEDICINE. 445 



to those of which the hsematozoa of malarial fever give us so remark- 

 able an example. In spite of these precise indications every search 

 for the infectious agent has hitherto been in vain, doubtless because 

 it is too small to be discovered by our means of investigation. It is 

 not the only one of which this can be said, for there is every reason 

 to suppose that hsematuric bilious fever and hydrophobia, among 

 others, belong to that category of parasitic affections whose germ 

 is yet unknown. It may be remarked that the researches of Schau- 

 dinn have shown that certain forms of Spirochteta observed in the 

 digestive tube of the mosquito {Culex pipiens) are sufficiently small 

 to go through porcelain filters and only become apparent to the 

 strongest magnifying powers when they are assembled in consider- 

 able numbers. Optical combinations will doubtless yet be discovered 

 that will permit us to see and study these excessively minute creatures. 

 Their investigation opens a way for researches of a peculiarly deli- 

 cate and interesting character. 



The facts recently acquired, or the questions recently raised in the 

 realm of helminthology, are also not without importance. Hardly 

 twenty-five j^ears ago we saw helmintholog}^ restricted to a descrip- 

 tion, or rather a summary enumeration, of the four or five intestinal 

 worms most widely found in Europe — that is to say, the two ta'nias, 

 armed and unarmed ; the ascaris, the oxyuris, and the tricocephalus. 

 To complete the survey there was also mentioned the filaria of Medina 

 as a sort of exotic curiosity. To show acquaintance with rarities, ref- 

 erence was made to the Strongylus gigas. As to the trematodes, we 

 were confined to the great aud little liver fluke, and the Bilharzia 

 was, for reason, discreetly alluded to. All this was comprised, in the 

 teaching of our medical faculties, in some three or four lessons. I 

 know something about it, as this was the plan on which I was educated. 



Note also that the French faculties and schools of medicine are 

 almost the only ones in the entire world that have a teaching chair 

 of natural history. It is true that the professor must, at the same 

 time, teach both zoology and botany in their applications to medicine, 

 as if it were possible to find, in the present state of scientific progress, 

 men capable of teaching with authority these two branches of natural 

 history that have long been so profoundly differentiated from each 

 other. In practice this difficulty was avoided, since the professor 

 taught that branch with which he was mostly familiar, leaving to 

 an associate the task of teaching the other. Thus it was that my 

 learned predecessor, Professor Baillon, who occupied the chair of 

 medical natural history of the Faculty of Paris for such a long 

 time, and whose botanical works had the greatest reputation, reserved 

 for himself the teaching of botany, his associate had, then, to teach 

 zoology. 



