FERTILIZATION ON PARTHENOGENESIS. 



143 



A great number of experiments have been performed in an 

 attempt to find out the conditions under which fertilization may 

 or may not be superposed upon butyric acid parthenogenesis 

 and to define the boundary line limiting the effect of the sper- 

 matozoon following parthenogenetic treatment. 



In production of parthenogenesis by butyric acid, eggs are 

 exposed to an optimum concentration of acid in sea water and 

 transferred to sea water at given intervals of time. Membranes 

 do not form in the acid, but only after transfer to sea- water, 

 and they are foimed best and in highest percentage after an 

 optimum exposure. 50 c.c. sea-water +2.8 c.c. n/io butyric 

 acid was found to be a good concentration, and the optimum 

 exposure in this concentration was usually about 20 seconds. 

 After either too long or too short an exposure the percentage of 

 membranes was less and they were less well formed. 



The general method of conducting the experiment is as follows: 

 Eggs are collected, washed three times, and divided into equal 

 lots; the lots are subjected separately to butyric acid using the 

 entire 52.8 c.c. for a graded series of time intervals (see Table I.). 



TABLE I. 



For each lot the acid solution previously thoroughly mixed was 

 poured over the eggs and at the given time eggs and butyric 

 acid solution were poured into vessel A, containing I liter of 

 sea-water -f 3 c.c. n/io NaOH, to stop the action of the butyric 



