214 



A. RICHARDS AND DONNELL J. GOOD. 



the egg is itself influenced by irradiation. A count, made as 

 carefully as possible, of the eggs of this experiment gives 54.25 

 per cent, as the average number developing. The data given 

 in the tables refer to the number of eggs which developed, not to 

 the total number of the experiment. These numbers were 

 verified by counts of sections as well as of the entire eggs. Of 

 the sections counted 53.5 per cent., and of the whole eggs, 55 

 per cent, were found to be developing, 'giving an average of 

 54.25 per cent. 



The B, C and D series were governed by one control. Since 

 all irradiations and fertilizations were at the same time this was 

 made possible. Experiment B was performed to test the effect 

 of two different lengths of exposure when sperm were irradiated 

 and used to fertilize normal eggs. They were subjected to 3- 

 and 15-minute exposure as in the A set. Samples of the control 

 and of the experiment were fixed at varying intervals after 

 fertilization. A study of these samples gave the following results : 



TABLE II. 



From this table we see that 20 minutes after fertilization the 

 first sample shows no difference whatever between control and 

 irradiated sets. The second sample taken 10 minutes later 

 shows no apparent difference yet in the sets. The third sample, 

 74 minutes after fertilization, shows the short irradiation still 

 the same as the control w r hile the 15-minute irradiation is slightly 

 behind. There is a marked difference in the percentages of 



