OBSERVATIONS ON THE GREGARINES OF HOLOTHUETANS. 287 



placed more in the interior of the cyst, and the sporoblasts 

 more peripherally. 



2. The stage found most commonly ^ was that of spores each 

 containing four nuclei (figs. 12, 13). In this stage the cyst is 

 completely filled with spores^ and with the exception of a few 

 sporoblasts occurring sparsely there is no unused protoplasm. 

 The spores are egg-shaped, one end broader than the other. 

 At the narrow end the membrane of the spore is continued 

 into a well-marked funnel, the lumen of which is, however, shut 

 off from the contents of the spore by a delicate diaphragm. 

 The cuticle is composed of two distinct layers, an inner thicker 

 one and an outer thinner one. Both layers appear to unite to 

 compose the funnel, which is formed of a single contoured thin 

 cuticle, but the diaphragm closing the mouth of the spore is 

 probably derived from the inner layer only. These structures 

 are best seen after treatment with a 10 per cent, solution of 

 sodium carbonate, which clears the contents of the spore 

 (fig. 14). In some spores the diaphragm lies close upon the 

 spore contents (fig. 14, h), in others it is raised up from them 

 and bulges into the funnel (fig. 14, a) . 



The spores contain four spherical nuclei (which, however, 

 like the nuclei of the sporoblasts, are often not stained in pre- 

 parations). The nuclei have a distinct membrane, and if care- 

 fully examined with a high power in a favorable preparation 

 can be seen to have the chromatin substance aggregated round 

 the periphery, being clear centrally. They are usually 

 arranged more or less regularly in the angles of a rectangle, 

 two being near the broad end and two near the narrow ; but 

 variations from this arrangement are common. In one instance 

 a spore was found to have three nuclei (fig. 13, c) ; two of the 

 ordinary size and appearance near the narrow end, and one larger 

 nucleus placed close to the broad end, and distinctly elongated 

 transversely to the long axis of the spore, as if about to divide. 

 From this it may be reasonably inferred that the two pairs of 

 nuclei placed at the narrow and the broad end respectively are 

 each the product of the division of a single nucleus, so that 

 ' These observations were made in the month of July. 



