THE CHROMATIN MASSES OF PIROPLASMA BIGEMINUM. 315 



in stained preparations, owing to retraction at death or to the 

 preparation of the film or smear and the difficulty of staining' 

 such fine processes. I have only seen oue good case of a 

 stained parasite with a protoplasmic process (text-fig. 23), 

 ah'eady mentioned. 



{6) The Chromatin of Free Parasites. 



Extra-corpuscular or free parasites are not very numerous, 

 and are found chiefly, as might be expected, at the edges of 

 the smear. Hegardiug epi-corpuscular forms, emphasised by 

 Liihe (4, 5) in the case of P. canis, I have only seen one or 

 two doubtful cases, not sufficiently definite to merit detailed 

 description, and my observations have been strictly confined 

 to stained specimens. 



The free parasites are nearly always more or less pyriform 

 in shape (text-figs. 37 to 42), occasionally rounded (text- 

 figs. 43 and 44), and are usually slightly larger in size than 

 the corresponding intra-corpuscular forms. 



The distribution of chromatin in free forms on the whole 

 closely corresponds with that found in pyriform intra-cor- 

 puscular parasites. Common cases are shown in text-figs. 

 37 and 39, where nucleus and blepharoplast are distinguished, 

 and in some cases an apical mass of looser chromatin (text- 

 figs. 37 and 38) is seen. In text-figs. 38 and 39 the strictly 

 pyriform contour is modified, approaching the fusiform. 



Occasionally the pyriform outline is seen to be modified in 

 the direction of its long axis. We then have interestino- 

 forms like those shown in text-figs. 40 to 42. These are long 

 and thin, and sometimes exhibit a prolongation of the pointed 

 extremity into a short, pointed cytoplasmic process ('' flagel- 

 lum"^ of some authors). Such processes, however, hardly 

 suggest great motility. These forms always possessed a 

 nucleus and blepharoplast, the latter at the pointed end. 

 Rarely, smaller chromatoid granules could, with difficulty, 

 be distinguished (text-fig. 42). These forms bear at least 

 1 Unfortunately tliis term (" flagellum ") is used, in tlie Protozoa, for botli 

 a cyto])lasniic process and a chromatic process rallier iudiscriininately. 



