304 KING. [Vol. XVII. 



4. That eggs fixed as soon as possible after the females had 

 been killed were not all in the same stage of maturation ; in 

 many cases normal changes were taking place exactly similar 

 to those found in a number of eggs that had been developing 

 in water for at least half an hour. 



The processes which are about to be described appear, there- 

 fore, to be nearly if not entirely normal, and they may serve 

 to throw some light on a stage in the maturation of the amphib- 

 ian Qgg which has not yet been worked out. 



In the youngest eggs obtained in the spring the germinal 

 vesicle usually lies with its longitudinal axis parallel to the 

 upper surface of the ^gg (PI. XXVIII, Fig. 6). It is gener- 

 ally found to be slightly larger than before the hibernation 

 period, measuring 0.31 mm. by 0.39 mm. in an ^gg with a 

 diameter of i.i mm. Its upper surface is never nearer than 

 0.08 mm., nor farther than 0.12 mm. from the periphery of the 

 egg, and in general contour it greatly resembles the germinal 

 vesicle of an earlier stage (PI. XXVIII, Fig. i). 



During the hibernation period, marked changes have taken 

 place in the nucleoli and in the structure of the chromatin 

 threads. The latter are no longer composed of a series of 

 short rod-shaped microsomes, as in PI. XXVIII, Fig. 5, but 

 have nearly the filamentous structure seen by Riickert ('92) in 

 the selachian ^gg, and by Born ('92) in the Qgg of Triton. The 

 axial part of each chromosome is composed of a number of 

 fine fibers, which are thicker at the center of the chromosome 

 where they stain quite intensely, and much finer at the periph- 

 ery where they stain very faintly and appear to run into the 

 fine reticulum of the nucleoplasm (PI. XXVIII, Fig, 16). The 

 fibers are placed radially to the longitudinal axis of the chromo- 

 some, so that in cross-section the chromosome presents "das 

 Bild eines Sternes mit dunkler Mitte," as described by Flem- 

 ming ('82) for chromosomes of like structure in the ^gg of 

 Siredon. 



Scattered among the axial fibers are a number of small, 

 round, deeply staining chromatin granules which apparently 

 bear no constant relation to the axial portion of the chromo- 

 some either in size, number, or position. In some chromosomes 



