46 HARRIETT M. ALLYN. 



time before fertilization (compare CC), but it is a decided drop. 

 Breaking this curve up as before, to show the proportion of 

 segmented and unsegmented swimmers, BB represents the 

 decrease in segmented swimmers, but B'B' shows a decided rise 

 in proportion of unsegmented swimmers, although the total 

 percentage of swimmers produced is less than in the fertilized 

 control or in the lot subjected to KC1 action for a brief time only 

 (see Table VIII. fertilized after KC1 I minute). In other words, 

 it appears that in the eggs which have been subjected to a slight 

 or slow KC1 action the spermatozoon is unable to induce cleavage, 

 so that we obtain many unsegmented swimmers, while in 

 eggs showing a greater or more rapid KC1 action the changes are 

 so great that the sperm cannot even induce differentiation, in 

 such a doubly stimulated egg. It seems that the effect of the 

 potassium chloride is a very decided one, which once having been 

 established in any egg, inaugurates such changes in it that it is no 

 longer capable of normal fertilization. (A few eggs may be able 

 to withstand the double action.) The longer the potassium 

 chloride acts the further the changes proceed, and the more 

 abnormal is the larva resulting from fertilization after KC1. In 

 short the eggs cannot endure this double stimulation any better 

 than they can polyspermy. 



These results, it seems to me, are exactly what would be ex- 

 pected. For if we consider the artificial stimulating agent as 

 acting in somewhat the same way upon the egg that the sperm 

 does, we would thus get in the egg some of the same sort of 

 changes set up which would take place in a fertilized egg. If 

 then we add sperm after this series is set going, the fertilization 

 is not to be expected to be normal. 



2. Cold and Sperm.- Eggs placed at a temperature of 9.5 C., 

 and fertilized after removal to room temperature, showed con- 

 siderable reduction in percentage of swimmers, especially seg- 

 mented ones, the reduction increasing with length of time, and 

 apparently more rapidly if the eggs were subjected to the con- 

 tinuous action of cold up to the time of fertilization than if an 

 interval of time at ordinary room temperature was allowed to 

 intervene between the application of the low temperature and the 

 addition of the sperm. Here, as in KC1 + sperm there is a ten- 



