THE TRYPANOSOMA BKDCII. 457 



arrangements of tlie micronaclei in these conjugating 

 organisms can be seen, such as a dot in one Trypanosoma 

 and a rod in the other, or two dots in one and one in the 

 other. The arrangement of a dividing rod and a dot can 

 be seen in fig. 20; that of a rod and a dot in fig. 21. 



Although it is difficult to definitely associate this junction 

 of two individuals with any immediate change in form, yet 

 we think, from the fusion of the micronuclei which takes 

 place, that it must be a true conjugatiou : and it is known 

 that this takes place in allied organisms, e.g. the Bodonin^, 

 which separate afterwards and go on as before, but perhaps 

 with renewed energy for division. 



After the fusion of the micronuclei we have not been able, 

 notwithstanding the examination of several hundred speci- 

 mens, to be sure of any constant further stages, but we imagine 

 that the most likely occurrence is that the fused micronucleus 

 lengthens out into the rod form, and then divides into two, 

 one for each organism, and that then the organisms them- 

 selves separate. In that case many of the forms which we 

 have seen, in which there is this rod form of micronucleus, 

 or in which the two micronuclei are separated, may be those 

 which have passed the fusion stage and are going on to 

 separation. In many, but not all, of these conjugating 

 forms the macronucleus shows signs of activity, i.e. it 

 enlarges and becomes oval or circular, and the chromatin 

 becomes aggregated at its margin, and we have thought 

 that these forms may be those in which conjugation is 

 ending, and which are about to Separate and to go on to 

 renewed longitudinal division. 



In our former paper we stated that we thought the 

 dotted forms described above (figs. 6 — 8) might be those 

 immediately following conjugation. But we have no 

 evidence of this ; and moreover, with very cai'eful staining 

 and illumination, these dots are seen to be of a little 

 different tint to the micro- or macro-nucleus. Sometimes 

 they are of a quite dark purple colour, instead of the 

 red nuclear colour, and they are moreover of very varying 



