694 H. M. AVOODfJOCK, 



have the same significance in the two cases. With regard to 

 the curious streaky substance, its position in relation to the 

 basal part of the fiagellum certainly suggests some association 

 with this organella; it seems to me not at all unlikely that 

 its presence is connected with the disappearance of the 

 trypanomonad character, and, indeed, a comparison of figs. 

 119, 149, and 150 prompts the query whether it may not 

 possibly represent the remains of a flagellar border which 

 has been actually absorbed by the parasite in the case of 

 some of these massive forms. 



Another cytological character often apparent in fairly old 

 cultures is vacuoHsation. One or two small vacuoles in the 

 cytoplasm may be seen occasionally in individuals of quite 

 regular form ; but, on the whole, in my cultures parasites 

 belonging to the definite types recognised above are free 

 from vacuoles. The occurrence of a few small vacuoles in an 

 individual doubtless signifies nothing very abnormal ; when, 

 however, the cytoplasm either appears practically full of 

 vacuoles, or else contains one or two huge ones (fig. 154), this 

 ought most probably to be considered as an unhealthy sign. 



Very marked indication of a disturbance in the mutual 

 balance of the various cell-constituents is frequently seen in 

 an irregular distribution of the nuclear organella^. Parasites 

 with two trophonnclei and a single kinetonucleus are not 

 uncommon (fig. 156). These are not to be interpreted as 

 individuals which are in an early stage of division, the process 

 having been begun by the trophonucleus. On the conti-ary, 

 they are the result of a division in which the nuclei have 

 been unequally apportioned between the two daughter-para- 

 sites. This is clearly shown by fig. 157, where the cytoplasm 

 is splitting in such a manner that one daughter-individual has 

 both the ti'ophonuclei and the other only a kinetonucleus. 

 The remarkable feature is that these forms without a tropho- 

 nucleus can live alone, at any rate for a certain length of 

 time, for I have observed four or five examples in the course 

 of examining my slides of this series (fig. 155). I have 

 never found an active, flagellated form with a trophonucleus 



