90 EICHAIID EVANS. 



The protoplasm soon loses its uniformly clear appearance 

 and becomes unevenly granular (PI. 2, fig. 9), a feature which 

 rapidly becomes more accentuated (PI. 2, fig. 10). The con- 

 tained granules or irregular blotches at this stage lie in round, 

 clear spaces in the protoplasm, but they soon increase in size 

 to such an extent as to fill the spaces above mentioned. At 

 the same time they acquire an oval or spherical form and 

 exhibit a certain amount of internal structure, in the form of 

 unevenly distributed granules of very small size (PI. 2, fig. 11a). 

 The subsequent change in the interior of the spherical 

 granules or yolk bodies, as they may be termed henceforth, 

 consists in the differentiation of a peripheral layer or coat 

 which sometimes, though not always, contains fine granules, 

 from a centre which invariably seems to possess a finely 

 granular structure (PI. 3, fig. lod). The yolk bodies have at 

 this stage attained their ultimate structure, and fill the cell in 

 which they have been formed. 



While these changes are going on a curious change takes 

 place in the character of the nucleus. At first granular, it now 

 becomes vesicular, or perhaps more correctly it presents an 

 appearance intermediate between the typical vesicular nucleus 

 with a solid nucleolus and a granular nucleus (PI. 3, fig. 

 IScZ, nu.). The cells seem never to possess more than one 

 nucleus. 



The yolk cells, as they may be termed henceforth, have 

 increased slightly in size during the changes above described. 

 However, they retain their individuality, though owing to the 

 pressure which they exert on one another they are often 

 polygonal in shape. In the fully developed gemmule they 

 are so pressed against one another that their individual outline 

 can be seen only with difficulty, which is in no way a remark- 

 able thing seeing that at no stage do they possess a definite 

 cell wall though having a well-defined cell limit. 



The yolk cells collectively, or the reproductive part of the 

 gemmule, as they may be termed, at no stage possess a 

 membrane, though in the fully mature gemmule they are so 

 pressed against the inner chitinous layer of the protective 



