HMMOPROTEUS NOCTUM 



521 



reduction, which results in four dyads, and then a second division follows, 

 leaving four monads or single chromosomes. The kinetonucleus now returns 

 to its old position outside and close to the trophonucleus, and the macro- 

 gamete is fully developed. 



Schaudinn was not able to trace out the reduction of the kinetonucleus, 

 but it ultimately consists of four chromosomes and a centrosome, which, 

 Woodcock points out, are not wholly sexual. 



Fig. 181. — Hcemoproteiis noctuce Celli and Sanfelice, 

 (After Schaudinn.) 



Formation of the male ookinete, and its development into the male 

 trypanosome. 



Zygosis. — This consists in the penetration of a microgamete into a receptive 

 cone, which has arisen from, the cytoplasm^^of the|^macrogamete on the side 

 where the nuclei are situated. ^^---^l-:^- - 



The only parts which enter are the^male trophonucleus, "^which isjreduced, 

 and the male kinetonucleus, which is not reduced, but which now undergoes 

 two divisions. The trophonuclei of the male 

 and female elements fuse, and form the fusion 

 spindle, at either end of which the kineto- 

 nuclei take up positions, and thus the zygote 

 is formed. 



Ookinete. — While zygosis is proceeding, and 

 even before the complete formation of the 

 synkaryon, the zygote becomes vermiform 

 and motile, and is therefore called an ookinete. 

 It consists of an anterior, hyaline, change- 

 able end, which is followed by a region of cyto- 

 plasm with vacuoles, then by a denser region 

 with the nuclear spindle just described, and 

 finally a rounded posterior end, full of granules 

 and haemozoin. From this posterior end a 

 portion of cytoplasm enclosing granules and 

 haemozoin, etc., is cut off, thus freeing the 

 ookinete of waste material. The spindle of 

 the synkaryon now consolidates to form eight 

 chromosomes, which will constitute the tropho- 

 nucleus, while the two kinetonuclei at either 

 end of the spindle, meeting together, form a 

 single kinetonucleus, which takes up a central 

 position inside the trophonucleus, and divides 

 into eight chromosomes, with a centrosome 



in its centre. The nucleus of the ookinete, therefore, consists of a central 

 centrosome, with eight surrounding chromosomes, around which lie another 

 eight chromosomes, bordering the periphery. 



But ookinetes are not all alike. On the contrary, Schaudinn describes three 

 kinds : — 



I. Indifferent Ookinete. — Cytoplasm clear, and staining faintly, with one or 

 two large vacuoles anteriorly, and having some granular material and haemozoin 

 still left. 



Fig. 182. — Hcsmoproteus noc- 

 tuce Celli and Sanfelice : 

 Development of the 

 Female Ookinete and 

 THE Female Trypano- 

 some. 



(After Schaudinn.) 



