﻿104 Proceedings of the Royal Physical Society. 



protoplasm is from a creature with two trophonuclei, one 

 behind the other, and with two kinetonuclei, one ac each 

 side and at the same level. From each of these there passes 

 forwards a flagellum and its undulating membrane. The 

 protoplasm now begins to split from the flagellum end 

 posteriorwards. Fig. 54 illustrates a pretty late stage, and 

 agrees with division as generally described in trypanosomes. 

 It is interesting to note that here the little basal granule can 

 be distinguished also about to divide, and bound to each 

 kinetonucleus by a very slender thread. The trophonuclei, 

 it will be seen, are beginning to assume the cross-barred 

 condition already described. 



This creature proceeds to split up further until it is in a 

 straight line, kinetonucleus to kinetonucleus in the ordinary 

 way. While this is the typical method, many interesting 

 variations occur with such frequency that they cannot be 

 neglected as abnormal appearances. During division the 

 animal is in constant and often very active movement, and 

 this is, I think, a potent factor in determining some of the 

 points. Fully developed trypanosomes are met with where 

 only the anterior third or so of the protoplasm has divided, 

 and it may sometimes be noted that one or both of the two 

 trophonuclei have slipped through between the blepharoplasts, 

 so that, at a later stage, such as Fig. 56, trophonuclei and 

 kinetonuclei are arranged alternately. When division is 

 complete, one finds that there will be one trypanosome with 

 the nucleus at or near the extreme posterior tip of the body, 

 and with the blepharoplast immediately in front of it, and 

 another with the usual arrangement, i.e., the blepharoplast 

 posterior to the trophonucleus. This method of division 

 explains trypanosomes in the condition of Fig. 57, and 

 specimens are often found with the trophonucleus in a still 

 more posterior position. Fig. 55 shows an even greater 

 difference between the daughter individuals. 



Fig. 59 is an interesting creature, in that it shows that the 

 nuclei of the daughter animals differ considerably in appear- 

 ance, and also indicates that one individual will most probably 

 have a much larger share of the protoplasm than the other. 

 This speciuien also offers something of an explanation of 



