INITIATION OF DEVELOPMENT IN CH/ETOPTERUS. 25 



TABLE II. 



AGENTS INDUCING POLAR BODY FORMATION, BUT NO SWIMMING LARV/E. 

 2}^ M potassium chloride in sea-water. 

 o.i per cent. i minute to 25 minutes. 

 0.5 per cent. 5^ minutes, sometimes 10 or 20 minutes, 

 i.o per cent. i minute, sometimes 3-6 minutes. 

 2.0 per cent. i minute to 10 minutes. 

 3.5 per cent. 4 minutes (in some cases). 

 5.0 per cent. 4 minutes (in some cases). 

 7.5 per cent. i minute. 

 10. o per cent. i minute. 

 15.0 per cent. 5 minutes (in some cases), 

 w/io acetic acid in sea-water. 



i.o per cent. i or 5 minutes. 

 Low temperature. 



9.5 C. i hour (in some cases). 

 12.5 C. 15 minutes. 

 De-aerated sea-water. 



10 minutes to i hour and 16 minutes. 

 Oxygen-saturated sea-water. 



16 minutes to i hour and 5 minutes. 

 n/io potassium cyanide in sea-water. 



20. o per cent. 

 Double potassium chloride, in some cases. 



TABLE III. 



AGENTS INEFFECTIVE IN INDUCING DEVELOPMENT. 



Potassium chloride, 2 % M in sea-water, 

 i.o per cent. i minute (in some cases). 

 7.5 per cent. 5 hours and 30 minutes. 



10.0 per cent. 5 hours and 30 minutes. 



15.0 per cent. i hour 55 minutes to 5 hours 30 minutes. 

 Mechanical agitation or nicking. 

 Low temperature. 



9.5 C. 15 or 30 minutes. 

 Sperm extract, by boiling. 

 Alcohol in sea-water. 



0.5 per cent. 3 minutes to 3 hours 15 minutes. 



2.0 per cent. 3 minutes to 3 hours 15 minutes. 



5.0 per cent. 3 minutes to 3 hours 15 minutes (except 40 minutes). 

 Oxygen-saturated sea-water. 



i o or 20 minutes (in some cases). 

 High temperature. 



30-3i.3 C. 5 minutes or i hour 30 minutes. 



33-34- 2 C. 5 minutes or 20 minutes. 



35-45 C. 5 minutes to 60 minutes (except perhaps 40, i minute). 

 Nitric acid. 

 Sulphuric acid. 

 Oxalic acid. 



