42 n. M. WOODCOCK. 



advanced; the septum is also still present. In figs. 41 and 42, 

 on the other hand, more of an encystment is recognisable, 

 the exact character of which has l)een described above. The 

 former is a section showing many nuclei, and no septum is 

 visible.^ Already it can be seen that the nuclei are of two 

 kinds, some (N) being- much larger than tlie others (»). In 

 fiof. 42 this difference in size has become accentuated. 



{h) Distinction of the multiplying nuclei into two 

 classes, somatic and germinal, and their 

 further history. 



In fig. 49 are drawn some of the nuclei from sections of 

 another Gregarine in a condition very similar to that in fig. 

 41. They show the earliest stages in this differentiation of 

 the nuclei into two kinds. A considerable change has 

 occurred in the nuclear constitution since we last saw it in 

 fig. 47. Some of the nuclei (the larger ones) have divided 

 less often than others, and are of an irregularly ovoid to 

 rounded shape ; the smaller ones are more uniformly ovoid. 

 In the large nuclei there is, in place of a dense, finely meshed, 

 chromatic network, either a very loose reticulum (a) or none 

 at all ; in the smaller, the chromatin is situated peripherally, 

 and is in the form of fairly even-sized rodlets or grains in 

 contact with the nuclear membrane. In all cases the rest of 

 the nucleus is filled with a non-staining nuclear sap. The 

 chromatin in the larger nuclei is in the form of irregular, 

 deeply-staining masses or lumps, with sometimes fine grannies 

 or chromatic dust besides, unevenly distributed throughout 

 the extensive nuclear sap. 



These two sorts of nuclei represent the division of the 

 nuclear material into a somatic portion, which eventually 

 breaks down and is absorbed by the cytoplasm, and a func- 

 tional or germinal portion which alone will form the nuclei 



' It may either have disappeared or never have been formed ; in sections 

 through another cyst at a similar stage there are traces of one, not so distinct, 

 however, as that in fig. 42. 



