236 



TREADWELL. 



the eggs treated with the KC1 solution and a few usually appear 

 among the ciliated embryos of a successful experiment. 



When laid, the egg of Podarke passes into the stage of the 

 first polar spindle, and remains in this condition until fertilized. 

 It is not at all uncommon to find among late cleavage stages 

 eggs which have escaped fertilization, and invariably they show 

 the first polar spindle. Treatment with the KC1 solution appar- 

 ently does not stimulate the egg to form the polar globules, for 

 I have not been able to find any of the latter, and in the one-cell 

 stages found in my preparations the chromatin is either packed 

 into a small, deeply staining mass, or scattered through the cyto- 

 plasm. Apparently, though I have not as yet sufficient evidence 

 to demonstrate the accuracy of this conclusion, if the causes 

 operating on the egg are such as to produce the former condition, 

 the further change, if any occurs, is purely cytoplasmic in its 

 character, while if the second condition appears, the egg may 



r 



i 2 3 



FIG. I. Division of cytoplasm without nuclear division. C. Chromatin. Pre- 

 served material. 



FIGS. 2 and 3. Like Fig. i but showing a more complete division of the cyto- 

 plasm. Preserved material. 



subsequently divide by a nuclear as well as a cytoplasmic 

 division. 



As illustrations of the former case, see Figs, i to 3. 1 These 

 were drawn from material preserved two hours and twenty minutes 

 after the transfer to sea water. At this time the eggs were in active 



1 A membrane is present in all of these eggs, but is represented only in Fig. I. 

 The drawing from preserved material shows a wider space between the egg and the 

 membrane than exists during life. 



