INITIATION OF DEVELOPMENT IN CH/ETOPTERUS. 



development without cleavage, induced in any way whatever, 

 by parthenogenetic agent or by sperm. There is space here for 

 a general account only, but I hope to give a more extended treat- 

 ment of the subject at another time. The hope was entertained 

 for some time that the right concentration or time of application 

 of potassium chloride might bring about cleavage, but the method 

 has never been successful for that purpose. 



In the experiments a certain number of cubic centimeters of 

 2^> M KC1 were mixed with a given amount of sea-water. The 

 eggs were placed in this solution after remaining 20-40 minutes 

 in ordinary sea-water (a delay which hastened and aided develop- 

 ment), and later were returned to normal sea-water after a 

 given exposure to the action of the KC1. 



A. Experiments to Determine the most Favorable Concentration 

 and Time for Development. Numerous experiments were per- 

 formed to determine the best concentration, and time of KC1 

 exposure to bring about the largest percentage of development. 

 Tables IV. and V. are taken from this set of experiments. By 

 comparing the tables it will be noted that there is a considerable 

 difference between the concentration and time inducing the 

 best percentage of maturation and that inducing the greatest 

 production of swimmers. Brief exposures give the best results for 

 maturation, but the greatest number of swimmers arises from 

 longer exposures. The best percentage of maturation, looper 

 cent, of eggs completing maturation, was gained by treatment 



TABLE IV. 



To SHOW THE BEST LENGTH OF EXPOSURE TO A GIVEN POTASSIUM CHLORIDE 

 SOLUTION TO INDUCE THE FORMATION OF BOTH POLAR BODIES. 



