64 HARRIETT M. ALLYN. 



Herbst ('07) found that when he fertilized eggs of Spharechinus 

 after subjecting them to the action of butyric acid he got poly- 

 spermy and abnormal larvae, but that this effect followed only 

 when a certain amount of time was allowed to elapse after the 

 application of the acid, before fertilization. With Clmtopterus 

 it may be said that in general any agent which induced artificial 

 parthenogenesis interfered with normal development when fer- 

 tilization was used after the artificial parthenogenetic agent. 

 The injurious effects were greater, usually, with increased time 

 allowed for the action of the parthenogenetic agent before 

 fertilization, but very brief action also interfered with normal 

 fertilization. It seems to me that these facts furnish evidence 

 that the development induced by an artificial parthenogenetic 

 agent is similar in its working to that induced by a spermatozoan. 

 If the primary effect of fertilization or of artificial stimulation is 

 regarded either as an increase in the permeability of the egg, or 

 a starting up of cytolysis, it seems reasonable to suppose that the 

 use of the two agents in the same egg should increase the permea- 

 bility to an excessive degree or cause too rapid or extensive 

 cytolysis, and therefore produce abnormal results. The time 

 factor also adds its effect, in that the farther development has 

 proceeded before the application of a second agent suited to 

 initiate development, the more difficult it is for such an agent 

 to produce its normal effect. 



6. Combination of Two Physico-chemical Agents. When we 

 consider the combination of two physico-chemical agents we have 

 a somewhat different proposition, although essentially the same. 

 In this case the physico-chemical agents may or may not dupli- 

 cate each other in reaction, according to their nature. If they 

 do act as duplicates their combination appears to lead to in- 

 jurious results, as in the case of adding sperm to artificial par- 

 thenogenesis. For instance when one solution of potassium 

 chloride was followed after an interval by another solution of 

 potassium chloride, practically no development followed. Matu- 

 ration was initiated as a result of the first treatment, thus showing 

 that the solution was effective, but when a second "dose" was 

 applied it was unable to produce its usual effect, indicating 

 that the reaction had already proceeded to a point where a 



