﻿Contr. toward the Embryol. and Anat. of Pol. pallipes (Hymenopt.). 149 



we think can rightly be called yolk nuclei, although the blastoderm 

 has not as yet been formed. These nuclei remain within the yolk, 

 never actively taking part in the formation of the blastoderm. Pre- 

 vious to the beginning of blastoderm formation they do not, as we 

 have shown, differ from the cleavage nuclei, and it would be hard to 

 find at this stage anything in them whicb could be looked upon as 

 degeneration. If the term yolk nucleus is restricted to those nuclei 

 which remain within the egg after the blastoderm is formed then 

 degeneration may at once occur in the yolk nuclei, but we see no 

 good reason for this late Separation of the two kinds of nuclei from 

 each other. If, on the contrary, we call yolk nuclei those which, 

 long before the blastoderm is formed, become separated by their 

 position from the cleavage nuclei, we cannot say that degeneration 

 does at once occur, for these we have shown are not as yet in any 

 sense degenerate. 



Methods. 



Many dirferent methods were used in hardening and staining 

 our specimens, but it would be of apparently little use to call atten- 

 tion to them all, and we give but a few methods which were used 

 more successfully than most of the others. Eggs were killed in hot 

 water, and in a few seconds an equal amount of a saturated aqueous 

 Solution of Sublimate was added. The eggs were allowed to remain 

 here for twenty to forty minutes, were washed and placed in 70°/ 

 alcohol. Another method was to heat a saturated aqueous Solution 

 of Sublimate to near the boiling point and then add to this an equal 

 amount of alcohol. This was then ponred directly over the eggs 

 and allowed to stand for ten to twenty minutes. The two methods 

 of staining which we used oftenest were iron-haematoxylin, generally 

 followed by Bordeaux red, and the safranin-methylen-violet, orange Gr, 

 triple stain. 



Zoological Laboratory, University of Wisconsin, 

 Madison, December 1904. 



