gS THE AMERICAN ARBACIA 



TABLE 3 



TIME IN MINUTES FROM FERTILIZATION TO FIRST CLEAVAGE 



TEMPERATURE 



7.0" 



8.0° 



9.0° 

 10.0° 

 11.0° 

 12.0° 

 13.0° 

 14.0° 

 15.0° 

 16.0° 



17.5° 

 18.0° 

 19.0° 

 20.0° 

 21.0° 

 22.0° 

 23.0° 

 24.0° 

 25.0° 

 26.0° 33.5 



27-5° 34-0 



30.0° 33.0 



31.0° 37.0 



32.0° no cl. 



TABLE 4 



time in minutes from fertilization to first, second and third cleavage 

 (from hoadley and brill, 1937) 



TEMPERATURE 1ST CLEAVAGE 2ND. CLEAVAGE 3RD. CLEAVAGE 



9.6° 295 486 528? 



12.0° 180 288 399 



15-2° 1 10.5 174.5 239 



18.1° 78.5 126 172 



21.3° 57-5 94 130 



24-1° 46-5 72.5 99 



26.9° 41.3 65.5 92 



30.0° 40 64 89 



