2G2 Robert Williclm Ilegiier. 



layer between the remains of the ''Keimhautblastem" and the vitel- 

 line membrane. They now vary from one another both in the size of 

 the entire cell and in that of the nucleus. The long cytoplasmic 

 processes which were characteristic of the pole-cell nuclei while 

 within the egg have disappeared; they have undoubtedly been re- 

 tracted until they now form a few blunt projections still suggestive 

 of pseudopodia (Fig. 22, h, c). The peripheral portion of each cell 

 consists of a lightly staining vacuolated layer, which was formerly, 

 before the pole-cell nuclei separated from the egg, the outermost 

 stratum of the ''Keimhautblastem" (Fig. 20, vac. st.). This layer 

 has spread completely over the surface of the protruded pole-cells, 

 and in consequence of this increase in area covered, has become thin- 

 ner; its stiiicture, however, is still the same as when it constituted 

 a part of the egg (Fig. 3, vac. st.). This is doubtless due to the 

 granular layer which, by its intervention, impedes the fusion of the 

 vacuolated portion with the denser cytoplasm within the cell. 



Just within the outer stratum is the granular layer ; this no 

 longer appears evenly distributed (Fig. 21), but now seems to be 

 massed in certain places and absent elsewhere, as shown in Fig. 23, 

 pdg. A close examination of sections (Fig. 22, jjdg) shows, however, 

 that the granules completely surround the nucleus as before but have 

 accumulated in the regions of the pseudopodia. These acciunulations 

 are often found in the granular layer of other stages and may even 

 be present in the pole-disc before the pole-cells are protruded (see 

 also Ritter, 1890, Taf. XVI, Fig. 3, and Noack, 1901, Taf. II, 

 Fig. 19). 



Between the granular layer .and the nucleus is a homogeneous 

 stratum of cytoplasm; this consists of all the protoplasm that sur- 

 rounded the nucleus before it reached the periphery plus that layer 

 of the 'Tveimhautblastem" in which the granules were suspended. 

 The nuclei of one of these cells (Fig. 22, h) shows a spireme, the 

 other (Fig. 22, c) a later stage in which the spireme has already 

 segmented into a number of chromosomes. 



As stated above, it sometimes happens that the pole-cell nuclei 

 do not all reach the "Keindiautblastem" simultaneously; those which 

 are delayed have difficulty in collecting enough cytoplasm for their 



