130 1'iiin rsity of California Publications in Zoology. I v "'- ' ; 



lithium carbonate solution. The slide is then differentiated in 

 iron iiluin and mounted in the usual way. 



With this method it is easy to get good results but the stain 

 is liable to precipitate in the cell and dissolve out unequally in 

 the iron alum, thereby producing artifacts. Method A is more 

 reliable for nuclear details and therefore has been used to con- 

 firm the results obtained by the other method. 



Till'; MORPHOLOGY AM) LIFE HISTORY. 



The experimental animals employed were rats and guinea 

 pigs, especially the former, which are very convenient on account 

 of the large number of parasites occurring in the circulation. 

 The trypanosomes first appear in the blood about eight to ten 

 days after inoculation and gradually increase in number until 

 numerous ( 100 or more to a microscopical Held), after which the 

 death of the rat ensues in about three days. The duration of the 

 disease may vary considerably, lint is usually from three weeks 

 to a month. 



The first trypanosomes that appear arc generally of the form 

 shown in fig'. 22 (PI. 15). These small forms are sluggish in motion 

 and often rotate about one extremity, so that they do not progress 

 much in any particular direction. The postcri<# extremity is 

 frequently rounded off. ami the thickness of the animal dimin- 

 ishes towards the anterior end. In the living animal a continua- 

 tion of the protoplasm can be seen extending beneath the tiagel- 

 lum lo the anterior extremity. 



in stained specimens the trophonuclcus can be seen as an oval 

 lightly-staining vesicle containing a distinct intranueulear cen- 

 trosome. In trypanosomes stained by method A this latter struc- 

 ture appears less dense than the kinetonuclcus. and. moreover, 

 the two differ in color in well-stained specimens, a further 

 evidence of their different nature. The kinetonuclcus is a densely 

 staining rod-shaped body situated (dose to the posterior extremity 

 and. compared with that of most pathogenic trypanosomes, is 

 rather large. Situated a short distance away from the kineto 

 nucleus is a round, somewhat lightly staining body from which 

 the flagellum arises. It is sometimes possible to trace tine con- 

 necting fibres between the kinetonuclcus and this end-bead. 



