INITIATION OF DEVELOPMENT IN CHyETOPTERUS. 



43 



ment was already initiated by potassium chloride. A set of eggs 

 was placed in i c.c. of 2 1 /? M KC1 + 50 c.c. sea-water. After i, 

 3, 15 and 30 minutes eggs were removed from the KC1 to sea- 

 water. Each lot was divided, part being fertilized and part 

 remaining in ordinary sea-water with no sperm, to form a KC1 

 control. After 15 and 30 minutes eggs were taken from the I and 

 3 minute KC1 controls just described, and fertilized. Thus 

 material was obtained showing the effect of an increasing length 

 of exposure to potassium chloride before fertilization, which could 

 be compared with eggs allowed to stand various lengths of time 

 in ordinary sea-water after a very brief exposure to potassium 

 chloride before fertilization. 



TABLE VIII. 



As may be seen in Table VIII. the eggs treated for one minute 

 with potassium chloride, and unfertilized, produced no swimmers, 

 whereas those of the same lot fertilized immediately after removal 

 from the potassium chloride showed many swimmers, but of 

 these 17 per cent, were unsegmented. The fertilized control 

 (no KCl) fertilized normally and onlj' two or three unsegmented 

 swimmers were found. 



In this particular experiment the record of polar bodies was 

 not taken, but in a similar experiment, of eggs in i c.c. 2^ M 

 KCl + 50 c.c. sea-water for one minute, 15 per cent, formed 

 the first polar body, and II per cent, formed the second also. 

 As before, no swimmers were formed. \Yhen eggs of the same lot 

 were fertilized immediately on removal from the KCl a large 



