FERTILIZATION ON PARTHENOGENESIS. 



Large quantities of eggs should not be treated with a small 

 amount of acid solution if good results are desired. In all my 

 experiments the same dilution of butyric acid has been used 

 (50 c.c. sea water + 2.8 c.c. n/io butyric acid) the entire 52 c.c. 

 has been employed and seldom has a larger quantity than 2 c.c. 

 of eggs been treated at the same tme. In order to avoid the 

 excessively large quantity of sea water necessary to dilute this 

 acid to a point where it would no longer inhibit membrane 

 production, a known amount of n/io NaOH has been added to 

 one liter of sea water into which the eggs and acid were poured: 

 a sufficient quantity was used that after the eggs and acid 

 were added the solution was still barely alkaline to phenolphtha- 

 lein, and finally eggs were observed under the microscope and 

 the percentage of eggs possessing membranes was noted. With 

 these points in mind we may turn our attention to the possi- 

 bilities of fertilization following such an optimum treatment 

 with butyric acid. 



(6) The Effect of Sperm, after Elimination of Membrane.- The 

 method used is that employed by Loeb on studies of this nature, 

 i. e., production of membranes by butyric acid, shaking the eggs 

 in a test tube to remove the membranes and subsequently in- 

 seminating with sperm. Loeb was sometimes doubtful as to 

 the efficiency of shaking in removing the membranes, some were 

 only torn according to his account and where a small percentage 

 of cleavages was obtained it was very convenient to consider 

 that these holes had again closed over and prevented entrance 

 of the sperm. If the shaking process is conducted quickly 

 enough after the production of membranes they are very easily 

 removed. Thus in one lot of eggs 90 per cent, of which revealed 

 typical membranes, shaking 1 was conducted 3 minutes after 

 being returned to alkaline sea water. Examination by means 

 of the microscope did not reveal the presence of a single membrane 

 out of 100 eggs counted. Six minutes after membrane produc- 

 tion, as nearly as possible the same amount of shaking was given 

 to another batch from the same lot, yet 30 per cent, of these eggs 

 still possessed intact membranes; nine minutes after, even 



'Shaking was conducted in a test tube 3 X 21 cm. containing eggs and sea 

 water. The tube was filled to one third its volume. 



