134 University of California Publications in Zoology. I v<lL - i; 



types t<> lie described below, is a further proof of its distinctness. 



In certain of the indifferent trypanosomes a small quantity of 

 the substance of the kinetonucleus is budded off and passes up the 

 middle of the cell towards the trophonucleus (PI. 15, figs. 9-12). 

 It swells up and eventually appeal's as a lightly staining vesicle 

 in close proximity with the trophonucleus. At times a succession 

 of these bodies is budded off from the kinetonucleus, giving an 

 appearance such as that shown in tig. 13. From the irregularity 

 of this phenomenon it is probably of no significance, but it may 

 lie found in all types of this species. 



Some of the indifferent trypanosomes early in the course of 

 infection proceed to the formation of a distinct type of trypano- 

 some known as the "stumpy forms" I PI. 16, tigs. 29-3-1). The 

 hitter are very obvious in preparations of the living parasite, as 

 they have a peculiar habit of slowly rotating about one extremity 

 and are extremely sluggish in all their movements. A free 

 Hagelliini is absent in the fully developed forms and moreover the 

 undulating membrane is not well developed. The posterior 

 extremity is bluntly rounded, and tile whole body of the animal 

 is very short in proportion to the width. Even in the fresh state 

 the remarkable dense and granular character .of the protoplasm 

 is noticeable. The average dimensions of these forms is about 

 18/x in length, and ifi in thickness. 



The protoplasm of such trypanosomes stains very densely and 

 usually contains numerous chromatoid granules, that seem to 

 arise from the trophonucleus. The kinetonucleus is very large 

 and close to tlie posterior extremity of the body; in (dose prox- 

 imity to it is situated a large end-bead from which arises the 

 short llagellum. The trophonucleus is a large, round vesicle con- 

 taining a centrosome relatively twice the size of that found in 

 lb,, indifferent form (PI. 16, tigs. 33-34). 



The first evidence of the development of the stumpy form is 

 seen in the trophonucleus. The intranucleiis centrosome divides 

 lie. niii. and one ball' passes out of the nucleus taking with it a 

 spout-like mass of chromatin (tig. 30). This becomes detached 

 fig 31), and pusses away from the nucleus (fig. 32) ; it finally 

 degenerates, thereby giving rise to some of the chromatoid 

 granules that are so common in the stumpy forms. The whole 



