VISCOSITY CHANGES DUKING MITOSIS 



423 



column in the form of fractions. The numerator represents 

 the number of eggs completely segmented, the denominator the 

 total number of eggs counted. 



In the third column also are recorded the observations made 

 during the progress of the tests. It must be pointed out that 

 these observations were necessarily very hasty, and are there- 

 fore not as accurate as they might have been if the observer 

 had had time to proceed leisurely. Usually the tests were made 

 at very frequent intervals, and all observations had to be com- 

 pleted in the shortest possible time. 



TABLE 1 



Three-second tests. Temperature, 24° 



ACTUAL TIME 



AFTER 



FERTILIZATION 



5 



' 2 



10 



i-2 



15 



171 



20 



22i 

 25 

 271 

 30 



32i 

 35 



m 



40 

 43 



46 



481 



50-51 

 51| 



52i 



STANDARD 

 TIME 



minutes 



4.9 

 7.3 



9.7 

 12.1 

 14.5 

 17.0 



19.4 

 21.8 

 24.3 

 26.7 

 29.1 



31.6 

 34.0 

 36.4 



38.8 



41.7 



44.7 

 47.1 



OBSERV.\TIONS 



Dark zone distinct in some eggs 



3 zones appear in some eggs; others lack zones, these 

 have polar body. 



No zones visible. All eggs have polar body. 



No zones. 



No zones. 



A few eggs show zones (perhaps 10 to 20 per cent). 

 Most eggs lack zones. 



Dark zone present, often it is not very sharply defined. 



No zones. 



No zones. 



No zones. 



No zones. The two pronuclei appear large, but they 

 are not yet apposed. 



No zones. 



No zones. The pronuclei are apposed. 



No zones. The pronuclei have fused. 



Most eggs lack zones. A few show the dark zone, but 

 it is not very sharply marked off. 



Eggs generally lack zones. 1 or 2 perhaps show dark 

 zone. 



No zones. 



No zones. Many eggs in mitotic elongation stage. 

 ' Some are beginning to segment. 



12/100 segmented. 



23 /50 segmented. This taken as the time of segmen- 

 tation. 



37 /50 segmented. 



