3 88 



WILSON GEE. 



the process of fertilization instantaneously effects a marked 

 change in the membrane of the egg. The permeability of this 

 to certain substances seems to be increased, thus adapting the 

 young developing individual to the interchange of materials 

 which is necessary to its development. 



There is also at this time a critical period in the nuclear 

 phenomena. The male pronucleus has entered and is becoming 

 acclimated to the new environment of the egg cytoplasm. The 

 maturation divisions are being concluded and the female pro- 

 nucleus preparing for union with the male pronucleus and the 

 formation of the first cleavage spindle. These things indicate a 

 great increase in the metabolic activity of the egg. 



(b) Effects of Higher Percentages on Development. It seemed 

 that if the effects of treatment prior to fertilization were so 

 decided, it would be well to test the period immediately after 

 fertilization. Accordingly, a lot of eggs were subjected twenty 

 minutes after fertilization to a graded series of alcohol to as high 

 as twenty-five per cent. The results of this experiment are given 

 in an accompanying table (see Table III.). Here it will be 



TABLE III. 



RESULTS OF TREATMENT OF EGGS WITH SEA-WATER SOLUTIONS OF ALCOHOL 

 FOR FIFTEEN MINUTES AT TWENTY MINUTES AFTER FERTILIZATION. 



noted that the lower percentages produce an effect that is at 

 least noticeable as compared with the control. However, it is 

 necessary to use percentages of ten per cent, and over to secure 

 the same effects at this period as are produced by two per cent, 

 prior to fertilization. 



The process of development is retarded by these treatments, 

 and particularly so in the higher percentages. In the first 



