424 



L. V. HEILBRUNN 



TABLE 2 



Four-second tests. Eggs fertilized at 4.30 'p.m. Temperature at 4. 



at 5.15 p.m., 25.8° 



p.m., 25.6° 



ACTUAL TIME 



18 



20 

 22 

 24 

 26 



28 



30 



32 



34 

 36 



38 



40 



4U 

 411 



42i 



21.7 



24.1 

 26.5 



28.9 

 31.3 

 33.7 



36.1 



38.6 



41.0 

 43.4 



45.8 



48.2 



OBSERVATIONS 



Three zones show plainly. 



In some eggs zones appear faintly. Most eggs lack 

 zones. A few polar bodies observed (5 min. after 

 fertilization). 

 No zones. Polar bodies generally present. 

 Most eggs lack zones. A few eggs have zones indicated. 

 Three zones show plainly. 

 Zones indicated in many eggs, never plain.. 

 Zones indicated in many eggs, never plain. 

 No zones generally (a few eggs have zones faintly 



indicated). 

 No zones generally. The second polar body is form- 

 ing (or has formed). 

 No zones. 

 No zones. 

 No zones. 



No zones. Pronuclei large, not apposed. 

 Zones show faintly in some eggs. Pronuclei large, 



apposed. 

 Zones appear; usually they are not very sharply 



marked off. Pronuclei large, apposed. 

 Zones show fairly plainly. Pronuclei usually broken 



down. 

 Zones show fairly plainly. 

 Zones usually show fairly plainly. In some eggs 



they appear indistinct. 

 Some eggs show zones. Most eggs lack zones. A 



few eggs are in the mitotic elongation stage. 

 No zones generally. Eggs have elongated and some 



have begun to segment. 

 8/25 segmented. 

 15 /25 segmented. 41§ minutes taken as the time of 



segmentation. 

 21 /25 segmented. 



