406 >IK- H. G, PLIMMER OX 



22. On the Blood-Parasites iound in Animals in the Zoo- 

 logical Gardens during the four years 1908-1911. By 

 H. G. Plimmer, F.R.S./F.Z.S., Pi-es.R.M.S., Pathologist 

 to the Society. 



[Received Marcli 2, 1912 : Head March 5, 1912.] 



(Plates XLIX.-LY.*) 



During the last four years I have examined the blood of every 

 mammal, bird, reptile, and batrachian which has died in the 

 Zoological Gardens, 6430 in all. In 447 of these, that is about 

 7 per cent., 1 have found blood-parasites. These 447 affected 

 animals belonged to 256 different species, as in many cases the 

 same parasite was found in several animals of the sa.me kind. 



Many of these parasites are described or recorded here for the 

 first time ; in other cases the hosts are new. In the tables which 

 follow I have indicated those which are new, or in new hosts, 

 by placing asterisks against the names of the animals in which 

 they were found. In spite of much generous help from Mr. R. I. 

 Pocock, F.R.S., Mr. Seth-Smith, and Dr. R. T. Leiper, to whom 

 my best thanks are due, it is impossible to be quite certain that 

 I have not given myself too much credit, partly on account of 

 the large amount of scattered literature on the subject, and pai-tly 

 on account of the constant change of names of animals on the 

 part of zoologists. 



Although the importance of the study of blood-parasites has 



only been recognised in comparatively recent years — that is 



since 1880, when Laveran discovered the hfematozoon of malaria 



in the military hospital of Constantine — it should be remembered 



that the first mention of a blood- parasite dates from 1841, when 



Valentin described an " entozoon" — as he called it — in the blood 



of a fish, Scdmo fario. Nowadays the importance of these 



parasites is well recognised, as well as the necessity of studying 



them comparatively, since we know that many of the gravest 



diseases of man and of animals are caused by them. I need only 



mention such diseases as malaria, syphilis, sleeping-sickness, and 



kala-azar of man, and trypanosomiasis (in its various forms), 



Texas fever, and the coccidioses of animals, to remind you of this. 



I have not attempted to give names to any of those parasites 



described here for the first time. In the present state of our 



knowledge it seems better to tabulate the hosts and give the 



o-eneral characteristics, or type, of the parasite. The custom of 



naming as new— very often with very absurd names — every 



similar pai-asite found in a new host is, I think, a very bad one. 



AVe can only name them reasonably when we know a great deal 



more about them than we do at present. 



The parasitic organisms I have found in the blood of animals 



* For explanation of the Plntc?' sei^ p. 117. 



