A H.EMOGREGAHINE OF MAMMALS 



103 



in the liver sections, as can merozoites lying free and easily distinguisliable by their colonr, 

 size anil nuclei. (Plate XII.) 



Laveran * has pointed out that the SL-hizont stage of hiemogregarines in reptiles is passed 

 in tlie liver, and Labbe has given much attention to this subject. As indicated, I have not 

 yet been able to ilccide wlictlicr diniorpliisna occurs, and if micro- and macromerozoites can 

 be distinguished. 



Before seeing the liver sections I was under the impression that the non-sexual cycle 

 was probably as follows : The trophozoite is set free from the erythrocyte as the travelling 

 vermicule, which eventually penetrates a cell of the liver or kidney, and gives rise to 

 schizonts in the form of cytocysts. In these the merozoites are formed which, after certain 

 changes, eventually escape into the blood stream, invade red blood corpuscles and so restart 

 the cycle of schizogony. 



So far, however, one has not been able to see anything like the travelling vermicule in 

 the liver sections. One jerboa was chloroformed, a post-mortem performed immediately, and 

 samples of the liver blood taken by means of a hypodermic syringe. This procedure, however, 

 yielded no fresh information. Only the ordinary trophozoites were found. Squash 

 preparations of the liver were made, but failed to aid one. The cytocysts and merozoites 

 were clearly seen, but no preliminary stage could be observed, and no changes took place 

 under the microscope. The form invading the hepatic cells looks like the trophozoite of the 

 peripheral blood, or, at the most, one of the swollen forms already mentioned. Is it, then, 

 possible that the travelling vermicule plays no part in this cycle ? Such is possibly the case, 

 or again, as Labbe asserts, for Lanlrstcrdla and Kari/olt/sii.'i, an isogamic conjugation may 

 take place between two of these free forms, and it may be the zygote so formed which can be 



seen penetrating the liver cells. Many, 

 however, disbelieve Labbe's conclusions, 

 which have not been confirmed by the 

 observations of Hintzef on Lanhestcrdla, 

 so possibly the freed trophozoite directly 

 iuvades the liver cell and becomes the 

 schizont, while the free vermicule is in- 

 teuiled to play a part in an extracorporeal 

 sexual cycle. This leads us to consider 

 the habits of the jerboa and the parasites 

 which it harbours. 



The rodent is a nocturnal animal. Nocturnal 

 living in holes in the desert, remaining habits of 



. ? jerboa 



invisible throughout the day, but found 

 hopping about in the evening and on 

 moonlight nights. It exists far from any 

 water, which it does not seem to require, 

 and its food probably consists of the minute seeds of the small plants which contrive to 

 exist in sandy wastes. The animal is easily caught in traps baited with millet. 



Both fleas and mites are found on the jerboa. The species of tSiphunoptcra present is 



Fig. 58. — Fle.\ of Jkkboa J (x 35 diam.) 



* 0. R. Soc. Biol., Paris (10) v. [i.] 1893 and (11) i. [li.] 189'J. 

 t Zool. Jahrb. Abth. f. Anat. xv. 4. 1902. 



