HMMOGBEGARINA CAN IS 



4S5 



zoite grows into the encapsuled form just described, all stages between the 

 two having been seen by Christophers, and in this way the cycle of schizogony 

 is completed . 



Sporogony. — The tick Eurhipicephalus sanguineus Latreille is very common 

 on the dogs in Madras. The female takes from two to four days to suck 

 the blood, which it only does once in its lifetime, but most of the blood is 

 taken in the last twenty-four hours. After sucking the blood it drops ofi, 

 and when examined at different periods the following sporogony can be 

 made out: — 



The encapsulated forms already described as existing in the blood pass 

 into the stomach, and the parasite escapes from the corpuscle, but is still 

 inside its own envelope. 



By elongation and passage of the protoplasm behind the nucleus, the oval 

 parasite becomes a vermicule. These vermicules must probably be looked 

 upon as macrogametocytes and microgametocytes. In any case they enter 

 young epithelial cells lining the lumen of the gut, in whose cytoplasm they 

 divide by fission, which in many cases takes place several times, resulting in 

 the secondary formation of four to eight vermicules lying in a pocket in the 

 cytoplasm of the cell. Two of these secondary vermicules, which apparently, 

 as a rule, do not differ in appearance, conjugate, and the nuclei fuse, and then 

 follows a throwing out of two large masses of chromatin from the nucleus 

 and the separation of a portion of cytoplasm. The former may represent 

 reduction, and the latter the separation of the body of the microgamete. 

 Anyway, as the result of this process there is formed an oocyst with a syn- 

 karyon, and therefore the conjugation results in a true zygosis. The oocyst, 

 still embedded in the epithelial cell, grows rapidly, and has a central clear area 

 and outer rim of protoplasm, with chromatin diffused in irregular masses 

 near the periphery. When about 14 ^ in diameter, the oocyst divides into 

 twelve to fourteen sporozoites (or sporoblasts) , which rather resemble vermi- 

 cules, but differ by being more globular and having a short oval nucleus. 

 These sporozoites escape into the lumen of the gut of the tick. 



Whether these bodies are sporozoites or sporoblasts is not known; neither 

 is it known how they get into the dog so as to complete the cycle of sporogony. 

 In other words, there is a great gap in the cycle of sporogony at this point. 



Haemogregarina bovis Marfoglioand Carpano, 1906. 



In Bos taurus in- Abyssinia. The parasites are 7 to 10 ^ in length, and 

 1*5 to 2 /X in breadth, and possess rounded ends. 



HaBmogregarina gerbilli Christophers, 1905. 



Found in the Indian field-rat, Gerbillus indicus, in which it produces only a 

 little anaemia. It lies in cysts in enlarged pale blood corpuscles as a vermicule 

 with a bent tail, and has a median nucleus and some chromatin dots. In the 

 louse HcBmatopinus stephensi, the parasite has been described as escaping from 

 its cyst and becoming a free vermicule, which gets in the ccelome, and there 

 encysts and becomes a large oocyst, growing up to 350 fjL in diameter. This 

 oocyst divides into numerous sporoblasts, which contain six to eight crescentic 

 sporozoites. These, when free, appear as sausage-like bodies, 15 by 4 [jb 

 with a distinct nucleus. 



There is, however, some doubt as to whether these cysts are really developed 

 from the hsemogregarine. 



Haemogregarina jaculi Balfour, 1905. 

 Synonym. — H. feaZ/owW Laveran, 1905. 



This parasite has been found in the jerboa {Jaculus gordoni) at Khar- 

 toum, and in /. orientalis in Tunis. It appears as a pale hyaline, homo- 

 geneous body, with the narrower end bent on itself, lying in a decolourized 

 erythrocyte. 



The trophozoite is found in a liver cell as an oblong parasite lying in a cavity. 

 This body can divide into three young forms, which presumably can grow 



