THR TRYPANOSOMA BRUCII. 455 



give it a ringed shape ; and it never extends completely across 

 the short axis of the organism, as is the case in the ordinary- 

 form. The chromatin is in the form of coarse threads or 

 rods, and there is almost invariably a clear unstained place in 

 the centre of the nucleus, which may contain a few scattered 

 dots of chromatin. The micronucleus is very distinct, as are 

 also the undulating membrane and flagellum. In this form 

 the thickened edge of the undulating membrane is most 

 distinct. 



Another form, which is also found principally in the blood 

 from the lungs in the mouse, is that shown in figs. 6 — 8, In 

 this, besides the macro- and the micronucleus, there arc a 

 number of dots staining very intensely, but of a much darker 

 colour than the micronucleus. In the one fig-nred the macro- 

 nucleus is still visible, but we have found these forms quite 

 full of these dots, with no visible macroniicleus. We thought 

 at the time of our first paper that this form was that following 

 conjugation, as a similar process occurs after conjugation in 

 organisms not far removed biologically from this one, but 

 this question will be discussed later. 



III. Reproduction op Adult Forms op Trypanosoma 

 Brucii. 



In our former paper we stated that we thought there 

 were two modes of multiplication by division of the adult 

 Trypanosoma, viz. by longitudinal division and by trans- 

 verse division. We now think that there is only one mode, 

 that of longitudinal division, and we think that the appear- 

 ances which we interpreted as transverse divisions were those 

 of amoeboid forms and not those of division. Besides this 

 means of reproduction by division, there is that of the forma- 

 tion of a plasmodial mass, from which amoeboid and adult 

 forms are given off, which will be mentioned later. This form 

 of reproduction is, we think, of the greatest importance and 

 interest. 



We will take first the method of reproduction by division. 



The process of longitudinal division down the long axis of 



