NEUKOSPOHIDIUM. 91 



The uninucleate spores, which are small gymnospores or 

 amasbulee, gradually pass out of the cavity around the parent 

 organism by more or less irregular apertures in the capsule, 

 and so invade the surrounding tissue of the host, and start 

 fresh infections in other parts of the nervous system of the 

 Cephalodiscus. 



Each spore on becoming free grows to about 2, 3, or 4 fx 

 in diameter, and division of its nucleus begins, while its 

 cytoplasm becomes granular and a little more opaque. In 

 this way young trophozoites are formed, such as those de- 

 scribed in the first paragraph of this section. 



All the cytoplasm of the spore-morula is not used up in the 

 formation of spores, and there is also nuclear material left 

 over. These residuary masses are clearly shown in our pre- 

 parations, and their fate may here be considered in some 

 detail. When the spores have left the parent spore-morula, 

 the latter has a faii'ly definite contour, leather more distinct 

 than during sporulation. The protoplasm is granular, and 

 there is usually a pale, centrally-placed nucleus. The proto- 

 plasm stains feebly, and the granules in it are distinct. The 

 residual nucleus is pale in colour, and reddish or brownish- 

 red after staining with hgematoxylin, and it thus stands in 

 marked contrast with the deeply purple nuclei of the spores in 

 the same preparation. In a few spore-morula examined little 

 or no residual nuclear matter was found, even after the 

 examination of all the sections into which they had been 

 cut. 



One or two rather more deeply staining dots may be seen 

 in the pale residual nucleus in some, rather rare, cases 

 (fig. 15). The residual nuclear matter is, as already stated, 

 the remains of the vegetative chromatin of the spore-morula, 

 the reproductive or generative chromatin being distributed 

 in the nuclei of the spores. Deeply staining granules of 

 chromatin are seen in capsules at this stage, sometimes in 

 two or three groups (fig. 15, chr.), but usually aggregated 

 towards the centre of the mass (fig. 17, chr.). These are 

 groups of chromidia, or small masses of chromatin, of about 



