140 J']. A. MINOHIN AND H. M. WOODCOCK. 



small, clear areas, like spaces, in the position in which they 

 were. In fig. 34 is another parasite which showed originally 

 a very similar condition as regards the granules; this has been 

 drawn since they disappeared. Two or thi'ee of the granules 

 are still seen, and the small vacuoles indicate the position 

 originally occupied by many others. It seems most probable 

 that these black " granules " are really minute globules of 

 oily or fatty substance, which are blackened by the osmic 

 acid used in fixation, and are liable to be dissolved away by 

 the frequent washings with xylol given to the slide, of course 

 after immersion-oil has been upon it. 



We entertain no doubt that this trypanosome belongs to 

 the species T. raiic, Lav. and Mesn. These authors, in des- 

 cribing this species, gave its size as from 75 fxto 80 fj. in total 

 length, by about fi in width (inclusive of the membrane). 

 Apparently, as has been so often the case, the species was 

 characterised solely from the full-grown individuals of the ordi- 

 nary type which were encountered, and no reference is made 

 to young forms or to variations in type. Further, Laveran and 

 Mesuil found trypanosomes which they regarded as belonging 

 to the same species in four species of Raia, namely K. 

 punctata, R. mosaica, R. clavata, and R. macro- 

 rhynclius. We do not know the name of the species of 

 Raia in which Ave found the parasite. The dimensions of the 

 largest individuals we have observed, however, are only very 

 slightly less than those above mentioned, and the general 

 appearance of the parasites, as shown in our figures, agrees 

 so closely with that of the individual figured in Laveran and 

 Mesnil's original account (7) that there is every probability 

 that the trypausome is the same in the two cases. Neumann 

 (15) has given the name T. variabile to a trypanosome 

 from R. punctata, principally or solely because he has 

 found variations in size and form in the parasite Avhich are 

 not referred to by Laveran and Mesnil ; though he states more 

 than once that his parasite resembles T. raiae closely and in 

 its largest form agrees with that trypanosome. As we have 

 described above, we have found forms of T. raite very much 



