122 E. A. MINCIIIN AND H. M. WOODCOCK. 



on the othei- hand upon the fact that they show very little, if 

 any, real affinity for the neutral red of Twort's stain. It may 

 be pointed out that, besides tlie facb of their being frequently 

 double, these grains differ from kinetonuclei in their staining 

 reactions. After Griemsa, tliey appear only reddish and have 

 not the characteristic dark purple or almost black colour 

 associated with true kinetonuclear elements; compare, for 

 instance, the intensely staining chromatic grain described by 

 Woodcock (23) in the case of a Halteridium of the 

 cliaffinch, which is (|uite distinct from the ordinary nucleus. 

 Again, their appearance after Twort's stain shows no resem- 

 blance at all to that of kinetonuclei. With regard to the 

 staining of these grains by Twort and ii'on-luomatoxylin, one 

 of us (E. A. M.) has found an interesting parallel in the case 

 of the blepharoplast (basal granule) of the flagellum of Try- 

 panosoma lewisi. In the multiplying (not the adult) 

 forms of this pai'asite the blepharoplast appears after Twort's 

 stain as a diffuse green patch, but after iron-haematoxylin it is 

 seen as a definite black granule. This comparison suggests 

 that the grains seen in H. rovignensis are centrosomic in 

 nature, but apart from the above facts we have no further 

 evidence to bring forward in support of this conclusion.^ 



We pass now to the consideration of the large forms of the 

 parasite. These are, as already mentioned, of two distinct 

 types : (1) Long, comparatively slender individuals, often 

 slightly curved or bow-shaped, which possess a small nucleus 

 (figs. 18-21) ; and (2) broad forms, oval or bean-shaped, 

 which have a much larger nucleus (figs. 22-26). In the wide 

 forms both ends of the hcemogregarine are generally similar 



' We have noticed one or two references to the occurrence of bodies 

 in other liaMnogregarines. which uiny perhaps relate to a similar 

 organella. Thus Miss Roliertsou (18) describes and figures two large 

 oval "red bodies," staining red with Giemsa, in H. vittatae; and again 

 (19) she mentions the occurrence of an eosinophile body or vacuole, 

 beside which is a sharply staining grain, in a hsmogregarine from 

 Pleuronectids. Whether, on the other hand, the " Plastinkeme " 

 described and figured by Prowazek (16) in H. platydactyli also 

 represent a corresponding body appears moi-e dou]:)tful. 



