682 STUDIES IN GENERAL PHYSIOLOGY 



thenogenesis will ultimately make hybridizations possible 

 which otherwise would be impossible. I intend to continue 

 these experiments. 



VIII. PRELIMINARY EXPERIMENTS ON PHASCOLOSOMA, FUNDU- 

 LUS, GONIONEMUS, AND PODARKE 



I will report briefly on experiments which I began but 

 was not able to finish, partly from lack of material and partly 

 from lack of time. My experiments on Phascolosoma were 

 carried further than the rest. I began with putting the 

 unfertilized eggs of this form in mixtures of 90 c.c. sea- water 

 + 10 c.c. 2i^n KC1 and leaving them in this solution from 

 thirty to one hundred and fifty minutes. I never saw an 

 egg reach the two-cell stage. Then stronger solutions were 

 tried, and now some of the eggs began to segment. When 

 the eggs were put into a mixture of about 30 c.c. 2-|n KC1 

 -+- 70 c.c. sea- water for about thirty minutes, they reached 

 a thirty- to sixty-cell stage. The appearance of the eggs 

 was so good that possibly in a continuation of these experi- 

 ments parthenogenetic larvae will be produced. In these 

 experiments I received valuable advice from Dr. Gerould of 

 Dartmouth College, who is thoroughly familiar with the 

 biology and embryology of this form. 



In Fundulus, a teleost fish, I succeeded in causing the 

 unfertilized eggs to reach the two-cell stage, but lack of 

 material prevented my carrying the experiments further. 



In my experiments on Gonionemus, a Medusa, I was assisted 

 by Dr.Murbach, who was kind enough to select the females for 

 me. Dr. Murbach had observed that by putting these animals 

 into the dark they can at any time be caused to lay eggs. 



My attempts (four experiments) to cause artificial par- 

 thenogenesis in these eggs have failed. All I was able to 

 accomplish was to force the eggs to become amoeboid and 

 creep about, but no segmentation occurred. 



