370 FRANK R. LILLIE 
systemic injury to the egg protoplasm at this time not received 
at other times, when the fact that maturation continues and polar- 
ity is preserved in these eggs, is considered. It would, there- 
fore, appear probable that the injury is to the process of fertiliz- 
ation itself, and this conjecture is completely confirmed by cyto- 
logical study. The most conclusive experiment in this respect 
is no. 27, the details of which are as follows: 
The eggs were fertilized at 9:28 a.m., September 4, 1909. 
Some of these were kept for control and all segmented normally. 
The remainder were centrifuged about 60 x 120 revolutions at a 
radius of 6 cm. in one minute, at the following times: 27A at 
9:58 a.M.; 27B at 10:03; 27C at 10:08; 27D at 10:12; 27E at 10:16. 
About 20-per cent of 27A segmented, 5 to 10 per cent of 27B, 20 
per cent of 27C, 50 to 60 per cent of 27D, and 75 to 90 per 
cent of 27K. Samples of the control and of each of 27A, 27B, 
27C, 27D and 27E were preserved at 10:31 and 10:43 a.m.? 
EXPERIMENT 27 
Eggs fertilized at 9:28 a.m., Sept. 4, 1909 
TIME AFTER | 
DESIGNA- CENTRIFUGED INSEMI- SAMPLES PRESERVED LIVING EGGS 
TION NATION 
(1) 10:314 a.m. All segmented 
27 Con- Not centrifuged | 
trol.. (2) 10:45 3a.M. 
27A ...|60 x 120 rev. in| (1) 10:30 a.m. About 20 per cent 
1 min. 9:58a.M.| 30min. | (2) 10:433 a.m. segmented 
27B..-.| 60 x 120 rev. in | (1) 10:303 a.m. About 5-10 per 
1 min. 10:03 a.m.| 35min. | (2) 10:433 a.m. cent segmented 
27C....| 60 x 120 rev. in (1) 10:304 a.m. | About 20 per cent 
1 min. 10:08 a.m.| 40 min. | (2) 10:44 a.m. | segmented 
21D \...\.00Rsx” 120 rev, an | (1) 10:31 a.m. |About 50-60 per 
1 min. 10:12 a.m.| 44 min. (2) 10:4435 a.m. | cent segmented 
27... -| 60! x" 120) rey, 1 | (1) 10:31 a.m. | About 75-90 per 
1 min. 10:16 a.m.| 48min. | 
(2) 10:45 a.m. cent segmented 
"Since the above was written this experiment has been repeated (Exp. 2, ’10), 
with the added precaution of preserving a sample of the normal eggs corresponding 
to each stage of centrifuging, in order to make certain of the stages of fertilization 
in each case. The results completely confirm those of experiment 27, and the 
sperm was found to be external in the most critical stage (37 minutes after insemi- 
nation in this experiment; see page 371). 
