466 J. R. BRADFORD AND H. G. PLIMMEK. 



of conjugation. This seems to us a very definite reason 

 for keeping the title we have used, which would correspond 

 to that given to a similar body in organisms not far 

 removed from these, in whicli conjugation is well known. 

 It has this fact in favour of its being a centrosome, that 

 it nearly always divides before the maci'onuclens does in 

 the longitudinal division described above. It is also 

 present through all the other stages of the Trypanosoma, 

 in the amoeboid and the plasmodial. Guignard^ has come 

 to the conclusion that the bodies generally called centro- 

 soraes have very variable characters, and that the so-called 

 blepharoplasts can be grouped under this name. So that it 

 is, after all, a question of terms, to which various meanings 

 are given by different writers. The main point which 

 induces us at present to adhere to the term micronucleus 

 is the behaviour of this body during the process of con- 

 jugation. Laveran apparently has not observed this stage 

 in the Ti-ypanosoma Brucii, hence his insistence on 

 the term blepharoplast, or centrosome, 



IX. The LiFE-flisTORY of the Trypanosoma Beucii. 



The life-history of this organism appears to be much 

 more complicated than that of the sewer rat Trypanosoma, 

 as described by Laveran and others, on account of the 

 presence of forms which we have described under the 

 headings of Conjugation, and Ama^boid and Plasmodial 

 forms, whicli do not appear to be present in the sewer 

 rat when infected with the Trypanosoma Lewisi. 



In our previous paper we placed those forms whicli are 

 shown in figs. 6 — 8, and which are described in section 

 II — 2, as those following conjugation, supposing that 

 these forms broke up into the amoeboid forms, and that 

 these again fused to form the plasmodia. Since that time 

 we have observed these forms with great care, and we 

 have been unable to find any definite intermediate stages 

 ' 'Ann. des sc. na(. botaii.,' 1897. 



