THE H^MOFLAGELLATES. 197 



nto the blood tliey soon die off. The microgametocytes, 

 here, arise from very young' indifferent Trypanosomes, which, 

 as they grow, reveal, by their pale, clear cytoplasm, coarse 

 pigment, etc., their assumption of male characters. A careful 

 examination of the adult microgametocyte shows that the 

 apparently single nucleus, which previous authors have 

 united in describing as, relatively, very large, is, in reality, 

 a highly complex organisation, and consists of eight groups 

 of double-nuclei (i. e. tropho- and kineto-nuclei in close 

 association, compare above p. 189) aggregated together. 

 As in the case of the corresponding forms in the gnat, the 

 trophonuclear elements have undergone reduction, and now 

 possess onl}' four chromosomes each ; the kinetonuclei still 

 have the normal number. The formation of the eight micro- 

 gametes and their separation from the parent-individual takes 

 place in the manner already described. 



Each microgamete is a very specialised organism, as is seen 

 from fig. 14 A, and the accompanying diagram. The body 

 is extremely slim and tapering, especially at the posterior 

 end, in marked contrast to that of a male Trypanosome in 

 the gnat; the anterior end, on the other hand, is not drawn 

 out, but acutely conical. The trophonucleus is greatly elon- 

 gated and has the form of a very long thread, extending 

 nearly the whole length of the body (fig. 14 a, t.), to which 

 it serves as an axis. The four chromosomes are strung 

 upon it like beads, at regular intervals. The kinetonucleus 

 (fc.) is also somewhat elongated and shows distinctly eight 

 chromosomes and an intranuclear centrosome (k.c). It 

 should be noted that the " tail " end is not the flagellar 

 end, but a posterior, whip-like extension of the cytoplasm 

 and trophic nucleus, and it has no relation whatever to the 

 locomotor nucleus and apparatus. As a matter of fact there 

 is here no free flagellum ; in other words, the kinetouuclear 

 spindle, which has formed in the usual manner the strongly 

 developed border of the undulating membrane (a.sjj.^) and 

 the eight strengthening myonemes (m.), does not extend 

 anteriorly beyond the limits of the cytoplasm. It ends in a 



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