5O HARRIETT M. ALLYN. 



above the number in potassium chloride alone. In the heat 

 experiments the eggs were placed in sea-water, in a warm bath, 

 the sea-water containing 2 per cent, or 7 per cent, of 2^/2 M KC1. 

 At intervals varying from 5 minutes to 1^2 hours they were re- 

 moved to ordinary sea-water at room temperature. With heat 

 alone segmented swimmers were obtained, but with the combina- 

 tion of the two agents, only typical "KC1" swimmers were to be 

 found. Thus while the combination made the KC1 experiment 

 more successful, on the other hand it really interfered with the 

 heat action. 



4. Cold and Potassium Chloride. (Table XII.) The action 

 of cold combined with potassium chloride was to decrease the 

 power of differentiation, but to increase polar body formation. 

 36.5 per cent, of the eggs in sea-water containing 2.5 per cent. 

 2 l /2 M KC1 at room temperature for 30 minutes, formed one or 

 both polar bodies and 16.5 per cent, formed swimmers, unseg- 

 mented. Of eggs from the same lot, in KC1 sea-water of equal 

 strength but at a temperature of 9.5 C., 79 per cent, formed one 

 or both polar bodies, but only 9 per cent, formed swimmers. The 



TABLE XII. 



cold alone for 30 minutes caused no noticeable development, but 

 applied for 60 minutes it brought about the formation of the first 

 polar body in 47 per cent, of the eggs, but no swimmers (in this 

 particular experiment). Thus the number of eggs extruding the 

 first polar body was as much increased, approximately, by the 

 combination of the two treatments, as the sum of the two effects 

 each considered alone (KC1 36.5 per cent, and cold 47 per cent., 

 -KC1 and cold together 79 per cent.). But the number of 

 swimmers was decreased from the number induced by potassium 

 chloride alone, although increased above that for cold alone, for 

 in the latter case there were no swimmers produced. It would 



