142 Transactions of the Society. 



Intestinal Organisms found in the Blood of Reptiles. 



Habitat Type 



Bull Frog — Bana catesbiana N. America Hexamitus 



Leopardine Snake — Coluber leopardinus . . . . Europe Trichomonas 



Indian Cobra— Naia tripudians India Trichomonas 



Box Tortoise— Cistudo Carolina N. America Hexamitus 



Three-banded Terrapin — Cyclemys trifasciata E. Indies Hexamitus 



Hog-nosed Snake — Heterodon simus N. America Trichomonas 



West Afrian FytJion — Python sebx W. Africa Trichomonas 



Angulated Tortoise— Testudo angulata .. .. S.Africa Hexamitus 



I now come to the intracellular parasites. 



Schaudin thought that the bird-trypanosomes, of which I have 

 just spoken, had an intracellular stage, and if this were so — it is 

 still extremely uncertain — they would form a bridge between the 

 widely separated extracellular serum flagellates and the intra- 

 cellular parasites of the blood cells. But so far as our knowledge 

 goes at present, we must keep these latter parasites quite separate 

 from those I have already described ; and as regards their classi- 

 ficatory nomenclature, it is better to keep at present to the general 

 name Hikmosporidia, but you must remember thiat the definition 

 and division are alike uncertain. 



It is convenient to divide the Hmmos'poridia into two classes : 

 the Heemogregarinidas, which in their adult stage have some simi- 

 larity to Gregarines ; and the Plasmodidae, which are apparently 

 naked, and are nearer related to the coccidia. The Plasmodidse 

 are again sub-divided into Plasmodium and Laverania. To the 

 former belong the malarias of mammals and the Plasmodium 

 precox, which causes the so-called bird-malaria. Laverania is 

 separated from Plasmodium by the long form of its gametes and 

 the small size of the schizonts, which are also scarcely ever found 

 free in the circulating blood. To this class belongs pernicious 

 malaria. 



I will take the Heemogregarines first ; and, for the sake of 

 those of us who are not biologists, or who do not belong to the 

 Biological Section, I will just define the terms used in describing 

 the cycle of these classes of protozoal organisms. The young 

 parasite in the animal cell is called a schizont ; this divides by 

 fission into two or more parts, and the process is called schizogony, 

 and the results of the division are called merozoites. Some of 

 these become changed, in order to carry on the cycle in the 

 definitive host, and are called sporonts. These are differentially 

 separated into male and female, and are called gametocytes. 

 After further differentiation, the male, being usually smaller, 

 becomes a microgametocyte, and the female, being larger and full 

 of reserve material, becomes a macrogametocyte. The male then 

 gives rise to microgametes, which fertilize the female cell, which 

 has further differentiated, and becomes a macrogamete. This con- 



