48 HARRIETT M. ALLYN. 



oxygen action, results entirely comparable to those in the 

 KC1 -f- sperm experiments. 



B. Combination of Two Physico-chemical Agents. A number 

 of different combinations were made, using potassium chloride 

 with other physico-chemical agents, in the hope that some other 

 agent added to the potassium chloride would induce cleavage. 

 The method met with little success. In fact in many cases the 

 results were similar, in their suppression of development, to those 

 produced by using a parthenogenetic agent and sperm. 



1. Double Potassium Chloride. A weak potassium chloride 

 solution (i c.c. 2^/2 MKC1 -f- 49 c.c. sea-water), a concentration 

 suited to induce maturation, was allowed to act for four minutes. 

 The eggs were then removed to sea-water where they remained 

 10, 20, 40, or 60 minutes. They were then placed in a second 

 potassium chloride solution, (5 c.c. 2^2 M KC1 -f- 45 c.c. sea- 

 water), a solution usually suited to induce the formation of 

 swimmers. The eggs were left in this second KC1 from 9 minutes 

 to 2 hours. Almost no swimmers were formed! Some changes 

 had apparently been initiated by the first "dose" of the potas- 

 sium chloride, which prevented the second "dose" from having 

 the effect it would have been expected to have by itself. Here, 

 as in the combining of artificial parthenogenesis and fertilization, 

 the time factor is important, that is, the length of time after 

 the initiation of development determines the extent to which 

 development shall have proceeded, and the farther it has pro- 

 ceeded, that is, the longer the time, the less possibility there is of 

 another agent inducing its normal reaction in the egg. 



2. Oxygen and Potassium Chloride. In the experiments with 

 oxygen and potassium chloride, application of oxygen excess to 

 the eggs while they were in potassium chloride made the experi- 

 ment less successful than with potassium chloride alone, whereas 

 used after potassium chloride, oxygen-saturated sea-water induced 

 the formation of a slightly larger percentage of swimmers than 

 the potassium chloride alone. Moreover a set of experiments 

 in which the oxygen content of the water was raised merely by 

 running a continuous stream of the gas through the water for a 

 short time before, and during the experiment, had as a result the 

 formation of a number of very normal looking blastulse (Fig. 8), 



