5o6 



TELOSPORIDIA 



containing the hsemozoin, and called the residual mass, or nucleus 

 de reliquat, is always left unsegmented. 



The blood- corpuscle now breaks up, and the merozoites, residual 

 protoplasm, and pigment are liberated into the blood stream, 

 where the effete matter and some merozoites are taken up by the 

 leucocytes and destroyed. 



The merozoite usually tries to enter a red blood cell and to start 

 again as a trophozoite, thus completing a cycle in the blood of the 

 human being who is acting as host. This cycle is called the cycle 

 of Golgi, or schizogony. Sometimes more than one merozoite will 

 enter a cell, thus giving rise to multiple infection. In such a case 

 they are generally of the same age, but this is not invariable. In 

 the red cell, under these conditions of multiple infection, some 

 observers have thought that the young trophozoites might con- 

 jugate; but this, together with the suggestion of further division 

 of the merozoite. We believe to be incorrect, though it must be 

 admitted that forms with a double nucleus can be seen. Wlien 

 such a binucleate form is seen nowadays, it makes the observer 

 think seriously of a possible flagellate origin, and inclines him to 

 support Sambon and Hartmann's classification, but never, as far 

 as We know, has anyone seen a flagellate merozoite in human 

 malaria. 



It will be seen that in going through the process of schizogony 

 one sporozoite becomes several merozoites, and that each of these 

 may again become several merozoites, so that the infection grows 

 unless kept in check by phagocytosis, and perhaps chemical action 

 or quinine treatment. 



Each parasite means a red cell destroyed and so much toxin 

 liberated into the blood stream. Hence in a certain number of 

 days (eight to twelve, as a rule) the parasites will have increased to 

 such a degree that their collective toxins, acting upon the organs of" 

 the body, upset the metabolism and produce an attack of fever. 

 This period of eight to twelve days is the incubation period of the 

 disease. 



It is possible that all the sporozoites develop into schizonts, and 

 there is at present no evidence that they develop into male or 

 female forms directly. If they do not do this, then the merozoites 

 must differentiate sexually; for in about a Week male and female 

 forms can be seen in the blood stream, and, moreover, very young 

 stages can be observed. 



The earliest form of a sexual parasite is like an ordinary merozoite, 

 but it grov^^s very slowly, and it never possesses a vacuole, and as it 

 grows its protoplasm becomes heavily pigmented and granulated in 

 the female, and lighter and clear in the male. The result is to produce 

 a female type of parasite called the macrogametocyte, or a male 

 type of parasite, the microgametocyte. So that there are three 

 types of parasite — the indifferent or schizont, the female, and 

 the male. 



The macrogametocyte is characterized by possessing a small, 



