TEMPERATURE AND ARTIFICIAL PARTHENOGENESIS. 133 



periods of exposure and low temperatures, a larger percentage 

 of blastulse are formed than at the temperature of the room. An 

 increase in temperature to 30 C., as in experiment 2, entirely 

 inhibited the development of the egg. 



Experiment ./. Asterias eggs were placed in the following 

 solution : 15 c.c. 2^;z KC1 plus 85 c.c. sea-water. This method 

 was suggested to me by Dr. C. H. Neilson. Same temperatures 

 were used as in the previous experiments* The eggs were re- 

 moved from the solution after the following periods : 5 min., 

 15 min., 30 min., 45 min., I hour and 2 hours. The results are 

 tabulated as follows : 



PERIODS OF EXPOSURE TO SOLUTION. 



23 

 11 



This experiment shows very clearly the inhibiting action of low 

 temperatures on the process of artificial parthenogenesis at short 

 periods of exposure to the solution. The period of exposure 

 necessary to produce development increases steadily as the tem- 

 perature is lowered, although the optimum period of exposure at 

 any temperature varies greatly according to the maturity of the 

 eggs. The development produced at a temperature of 2 C. 

 after two hours' exposure, was shown not to be due to the low 

 temperature alone by control experiments in which eggs in normal 

 sea-water were kept at this temperature. No development by 

 means of low temperature alone can be obtained, unless the eggs 

 are exposed to the low temperature from three to five hours. At 

 30 C. again practically no development occurred. 



We now turn to the effect of variations in the temperature on 

 the process of artificial parthenogenesis when produced by the 

 action of specific ions. 



Experiment j. Asterias eggs were placed in the following 

 solution: 5 c.c. n/io HC1 plus 100 c.c. sea-water. This is a 

 method l which has been elaborated by Loeb and Neilson and 

 with favorable lots of eggs yields a very high percentage of de- 



1 Loeb, Fischer and Neilson, Anhiv fi'ir die ges. Psychologic, 1901. 



