STUDIES ON CEYLON H^:\[ATOZOA. 757 



strong infections to react to the presence of the parasite 

 by the formation of internal masses resembling- the mucoid 

 globules described by Leger and Duboscq (8 a). 



Formation of Sporozoites. 



•The further development of the parasite culminates in the 

 formation of eight sporozoites. A membrane is secreted 

 round the protoplasm, forming a kind of cyst-wall, but it 

 appears to be thin and not very resistant. Fig. 46 shows an 

 early stage where there are only two nuclei present. Subse- 

 quent divisions occur, and appearances such as fig. 48 ai-e 

 produced, where the lai-ger nucleus at one end of the creature 

 is preparing for division. Finally (see figs. 49-53), the 

 protoplasm segregates round the nuclei, and there are pro- 

 duced eight individuals; these when fully developed show 

 considerable resemblance to the free motile forms found in 

 the lumen of the intestine, and are of much the same size. 

 The sporozoites are set free in the wall and pass out into the 

 blood-spaces (see fig. 47 c, 54-56), where they can be dis- 

 tinguished from the corpuscles of the leech by their shape 

 and characteristic nuclear appearance. 



There is a well-marked correlation between the processes 

 of digestion in the leech and the condition of the parasite. 

 In a recently fed leech the free motile forms are numerous in 

 the intestine but no multiplicative stages are to be seen in 

 the wall. Later on the haemogregarines have penetrated the 

 wall, but only the earlier stages are present. Still later ripe 

 cysts with fully formed sporozoites are found in considerable 

 numbers in good infections. Quite late towards the end of 

 digestion, when the crop is empty, the sporozoites have for the 

 most part escaped into the blood-spaces, and the intestinal 

 wall is once more almost free from parasites. 



I have not been able to carry my investigations beyond 

 this point, and cannot say by what means the hferaogregarines 

 are passed back into the blood of the tortoise. In spite of 

 much searching I have never found motile stages of the para- 



