TEMPERATURE AND ARTIFICIAL PARTHENOGENESIS. 13! 



moved to fresh sea-water at the temperature of the room. After 

 removal to the room temperature the eggs were carefully ex- 

 amined from time to time to determine the exact proportion of 

 segmentations and swimming larvae produced by the same solu- 

 tion at the four temperatures mentioned above. Great care was 

 taken that, with the exception of temperature, all the conditions 

 affecting each lot of eggs might be identical. 



The following eggs and methods were used : Arbacia eggs, 

 action of concentrated solutions of MgCl , NaCl, and of sea- 

 water concentrated by evaporation ; Asterias eggs, action of 

 acids and a concentrated solution of KC1 ; AinpJiitrite eggs, action 

 of Ca(NO 3 ) 2 . Each solution was tried at the four temperatures 

 mentioned above. "All these solutions, with the exception of the 

 acids and the Ca(NO 3 ).,, are of a higher osmotic pressure than 

 the sea-water, and affect the eggs through the extraction of 

 water. In the case of the acids and Ca(NO 3 ) , the osmotic 

 pressure remains unchanged, and the fertilization is ascribed to 

 the specific action of the H or Ca ion. 



We will consider first the effect of variations of temperature on 

 the process of artificial parthenogenesis when produced by those 

 solutions which extract water from the egg. 



Experiment i . Arbacia eggs were placed in the following so- 

 lution : 50 c.c. 2.y 2 n MgCl plus 50 c.c. sea-water, and were 

 removed to normal sea-water at intervals of I, 2, 3^ and 5 

 hours. The following temperatures were used: 30, 23, 11, 

 2 C. Only a small proportion of swimming blastulae were 

 formed at a temperature of 23 C. and about half as many at 1 1 

 C. No development took place at 30 C. or 2 C. This was 

 not a successful experiment, as only a small percentage of eggs 

 segmented at all. An increase and a decrease in temperature, to 

 30 C. and 2 C. served equally well to entirely inhibit segmen- 

 tation. 



Experiment 2. Arbacia eggs were placed in the following so- 

 lution : ii c.c. 2 l / 2 J i NaCl plus 89 c.c. sea-water. Same tem- 

 peratures and periods of exposure to the solution as in experi- 

 ment i . The results of this experiment will be given in tabulated 

 form as follows : 



