570 Gideon S. Dodds. 



3. Distinctive Characters of the Earty Germ-cells 



A consideration of the features which characterize the early 

 germ-cells is of interest and importance. It is desirable to see 

 what are the earliest differences which have enabled various 

 workers to recognize them, to distinguish them from the body 

 cells among which they lie, and to see what light we may thus 

 get upon their nature, manner of setting apart, and relation to 

 the soma. 



It is common to speak of the early germ-cells as large, rounded 

 cells which stain faintly. They are also generally found to re- 

 tain yolk spherules long after they have been absorbed in the sur- 

 rounding cells. We have already seen that the earliest gonocytes 

 are found associated with entoblast, and as a general characteris- 

 tic of these cells it is often stated that they resemble entoblast. 

 Another common description is that they are cells that retain 

 their primitive characters for a considerable time. All these are 

 but different ways of describing the same condition. The absence 

 of mitotic figures during a considerable period is also- commonly 

 remarked, and it is this feature that accounts for their larger size. 



The presence of a considerable amount of yolk in their cyto- 

 plasm often obscures the nucleus, so that it is difficult to study 

 its details. Several observers state, that in early stages, they can 

 detect no nuclear differences between the germ-cells and body 

 cells other than the differences in size which early becomes mani- 

 fest. In some cases it has been noted that in later stages the 

 nuclei of the former stain less deeply than those of the surround- 

 ing body cells. Beard ('02 c) found that the nucleus of the germ- 

 cell is often bilobed. I do not recall that any other writers 

 mention this feature, so I cannot tell how general it is. 



One other feature of the germ-cells should not be forgotten; 

 that is, their amoeboid shape during a part of their history. This 

 feature, of course, is directly related to the ability of the cells to 

 execute independent movement. 



From a study of the literature it appears that the differences 

 which mark the germ-cells of vertebrates, arise gradually, and 

 are due more to changes in the surrounding cells than to changes 



