THE H^MOFLAGELLATES. 247 



ai'e formed, and the reduction of the chromosomes of the trophonuclear parts, 

 from sixteen to eight, occurs at this time. The formation and liberation of 

 the microgametes (fig. 34), the maturation of the megagametoeyte and the 

 fertilisation of the megagamete (fig. 35), all take place, according to the 

 author, in the same manner as in Trypanomorpha (Halteridium) 

 noctute. The microgametes themselves are constituted on the same Try- 

 panosoma plan, allowance being made for the different number of chromo- 

 somes. With fertilisation' and the subsequent formation of the vermiform, 

 motile ookinete, the life-cycle of Trypanosoma (" Hsemamoeba") zie- 

 manni is completed. 



It only remains to add that " recurrence " is produced in the usual way, 

 by parthenogenesis of female forms remaining over in the blood of the bird. 

 The only point requiring notice is that the rejuvenated parasite, instead of 

 giving rise to a single individual of any type, undergoes multiple division 

 like an ordinary ookinete and produces many little Trypanosomes. 



(b) Evidence in favour of a corresponding Dige- 

 netic Life-cycle in other Trypanosomes. 



Since Schaudinn^s work was published, evidence has been 

 accumulating which tends to show that the two examples so 

 brilliantly investigated by this author are not isolated cases, 

 but are rather to be regarded as, if not in every way typical, 



four such in the act of being set free in this same parasite. MacCallum 

 (72) also observed the same number liberated in a species of Halteridium, 

 and, moreover, the actual fertilisation of a megagamete. Compare also 

 the " Poly mitus "-forms of earlier authors, which were simply detached 

 "flagella" or gametes. Whether the occurrence is due to unfavourable 

 circumstances (e. g. removal from the body) is not certain, but it does not 

 seem to be quite normal, the number of gametes, for instance, being, at any 

 rate in the first named case, only half the normal number produced in the 

 gnat. Is this possibly consequent on the non-completion of the reduction 

 phenomena.'^ 



' Details of the process are not given, but the writer would point out 

 that the penetration of the microgamete into the megagamete is, most 

 probably, by the opposite end to that which moves first in Trypano- 

 morpha, namely, the non-flagellate end. This would be in accordance 

 with the behaviour of the parasites as regards attachment, agglomeration, 

 etc. Probably also in this case (it appears so, indeed, from Schaudinn's 

 figure) there is a true flagellar prolongation posteriorly to act as a steerage 

 orsan. 



