I!lll!l l Tin Lift History of Trypanosoma Dimorphon. 131 



These forms may divide (PL 16, figs. 27-28) but eventually 

 they grow up into a form of trypanosome intermediate between 



two extreme types i lies. 23-26). In consideration of the facts <>!' 

 their development and subsequent life-history these small forms 

 may be regarded as immature indifferent forms. The fact that 

 they divide is no evidence (if their maturity, for in T. lewisi the 

 corresponding immature forms also multiply (Salvin-Moore 



llivml and Illlldie. 1908). 



The type dl' trypanosome resulting from the growth of these 

 small forms is must abundant during the earlier stages of infec- 

 tion. Its form is shown in PL 15. figs. 1-3, from which it may be 

 seen that the posterior extremity is rounded off, and the bodj of 

 t he trypanosome tapers gradually towards the anterior extremity. 

 \ii part nl' the flagellum is free, a very fine continuation of pro- 

 toplasm extending to the very tip. The movements of these forms 

 are rather sluggish 5 the parasites slowly wriggling amongst the 

 red cells, and often describing circles. Their average dimensions 

 are about 18/u in length and 2/i in thickness, but they vary con- 

 siderably. 



The protoplasm stains rather densely, especially with method 

 A. and. as in the immature forms, consists of a tine reticulum 

 generally free from granules. The flagellum originates from an 

 end-bead which is distinct from the kinetonucleus, and usually 

 lies a little to one side of it. 



Both the nuclei resemble those described above with the ex- 

 ception that sometimes the trophonucleus may be slightly longer 

 than in the immature forms. These trypanosomes multiply by 

 longitudinal fission, the first sign of which is seen in the kineto- 

 nucleus. This seems to swell up. resulting in the formation of 

 an oval vesicle (fig. 2) throughout which the chromatin is 

 evenly distributed. The chromatin then aggregates together in 

 the form of a band lying across the middle of the vesicle, which 

 now becomes slightly drawn out in a longitudinal direction. This 

 band then divides transversely and the two halves move apart 

 (fig. 3), one of them usually approaching the trophonucleus, 

 and apparently without any further changes, beyond the dis- 

 appearance of the vesicle, constitute the two daughter kineto- 

 nuclei. During this process we have uever been able to dis- 



