﻿Tryjpanosome found in Pontobdella. 



103 



may separate quite simply while their long axes are parallel to 

 - each other, or may turn out from each other while still joined 

 by their posterior ends till the long axes form a single straight 

 line (Fig. 37). Or, again, a rotation of the two nuclei and the 

 two kinetonuclei may occur within the protoplasm before 

 any sign of division of the cell-body can be distinguished. 

 A strange appearance may sometimes be presented by forms 

 in which the protoplasm is only partially divided, but where 

 one of the developing flagella has got ahead of the other, 

 thus giving the impression of two animals at different stages. 

 Very misleading forms may be found, in which the tropho- 

 nuclei are proceeding to divide again before the division of 

 the protoplasm (Fig. 49). These figures — and ones where 

 there are four nuclei and two blepharoplasts, as Fig. 50 — are 

 very suggestive of conjugation, and might be interpreted as 

 nuclei undergoing the last reduction division before fusion. 

 One might with great ease fall into this error in material 

 where these appearances crop up singly. If, however, a 

 sufficient number of specimens are reviewed, it becomes 

 abundantly clear that they are not due to conjugation, but 

 really illustrate multiple division. Fig. 51 shows obvious 

 division into four, and affords an explanation of the four 

 nuclei in Fig. 50. I may here add that division into three is 

 a not infrequent appearance in (Figs. 53 and 52) material 

 where active multiplication is going on. The protoplasmic 

 features in all these stages, and also in those about to be 

 described, can be most beautifully made out in the living 

 specimen, although no very striking changes can be observed 

 on the one individual. The last stages, i.e., the final separa- 

 tion of the daughter individuals, was, however, followed in 

 the live state. The division of the trypanosome stage, which 

 may upon occasions be quite unequal, presents some features 

 of interest. 



The blepharoplast and flagellum usually divide before the 

 trophonucleus, but there is no sort of regularity in their 

 relations. I have not been able to observe the division of 

 the flagellum, and cannot say anything as to whether it 

 really splits or is re-formed, but I incline towards the former 

 view. The usual point of departure for division of the 



