216 SPOKOZOA. 



fully developed gametocyte is of an elongate sausage-shape^ 

 and almost completely encircles the nucleus : it shows a central 

 nucleus and a number of pigment granules distributed through 

 its cytoplasm. Gametocytes are distinguishable as male and 

 female. Male gametocyte possesses a hyahne cytoplasm, 

 staining a pale blue or pinkish colour with Romanowsky 

 stains, and a rather larger nucleus consisting of a membrane 

 enclosing a number of fine chromatin granules (fig. 104, B^, C^). 

 Female gametocyte has a denser cytoplasm, stains more deeply 

 blue, and possesses a more compact nucleus (fig. 104,5^, C^). 



Further development of the gametocytes takes place in the 

 fly, Lynchia maura. The male gametocyte produces male 

 gametes by exflagellation, the female gametocyte gives rise 

 to a single female gamete, and fertilization produces a zygote, 

 which is a motile vermicule or ookinete. The ookinetes 

 penetrate the hinder portion of the mid-gut of the fly and 

 produce pigmented oocysts on the outer surface of the wall. 

 The mature oocyst (fig. 105, B) measures about 36 jx in diameter, 

 and gives rise to a very large number of sporozoites (fig. 105, 

 G, D), measuring up to 10 /x in length. These are set free by 

 the rupture of the cysts, invade the salivary glands of the 

 fly, and are reintroduced into the body of the pigeon. 



Remarks. — Acton and Knowles (1914) studied the develop- 

 ment in the pigeon and concluded that schizogony takes place 

 only in the lung, but other observers have shown that it takes 

 place in the endothehal cells of the blood-vessels of other organs 

 as well. Clean pigeons exposed to infection by infected flies 

 show young gametocytes in the blood in about four weeks, 

 during which schizogony takes place a number of times. 



Ed. and Et. Sergent were the first (1906) to transmit the 

 infection experimentally to pigeons in Paris by means of 

 infected flies {Lynchia maura), received from Algiers. The 

 asexual cycle as occurring in the endothelial cells was first 

 described by Aragao (1908). Helen Adie (1915), working in the 

 Punjab, was the first to follow the sporogony of the ookinetes in 

 L. maura, and later, working at Algiers (1924, 1925), confirmed 

 her previous work in India. According to her researches, 

 flies which have hved on infected pigeons for ten to twelve days, 

 during which they fed daily, showed all stages of development 

 of the parasite from the ookinete to the sporozoites in the 

 salivary glands. 



De Mello and de Sa (1916) have described a process of 

 schizogony in Hsemoproteus columhse taking place in schizonts 

 which were originally in the red blood-corpuscles and then 

 became free in the plasma. If their observations were correct, 

 they must have been dealing with a species of Proteosoma. 

 These observations are recorded under Proteosoma cohimbse 

 (de Mello & de Sa). 



