Vol. XXXVII. October, 1 91 9. No. 4. 



BIOLOGICAL BULLETIN 



NOTES ON THE EFFECT OF X-RADIATION ON THE 

 DEVELOPMENT OF CUMINGIA EGGS. 1 



A. RICHARDS AND DONNELL J'. "GOOD, 

 WABASH COLLEGE, CRAWFORDSVILLE, INDIANA. 



The energy of X-rays and of radium rays has been used by 

 a number of investigators during recent years for modifying the 

 normal course of development in living eggs. It has been sought 

 to show by this means what efficacy these rays possess in altering 

 vital properties of protoplasm, and to gain additional information 

 concerning the normal as well as the abnormal reactions of living 

 matter. One of us (Richards, 1914) had studied the effects of 

 X-radiation upon early cleavage and development of Planorbis, 

 a gasteropod, and it seemed probable that Cumingia, a lamelli- 

 branch, would offer interesting comparative data as well as give 

 results of importance in themselves. For this reason the experi- 

 ment herein described was performed. 



Cumingia tellinoides is a form the eggs of which are very 

 frequently used for experimental purposes at Woods Hole. The 

 eggs and sperm are easily obtained separately, and may there- 

 fore be subjected to radiation either before or after fertilization. 



The normal development of Cumingia is not as well known as 



1 During the month of August, 1914, while working at the Marine Biological 

 Laboratory at Woods Hole, the senior writer performed experiments to test the 

 effect of x-radiation upon the eggs of Cumingia. This experiment yielded results 

 which would have justified a much more extensive study of the behavior of these 

 eggs under the stimulation of x-radiation, but circumstances have prevented its 

 repetition. In spite of the fact that the experiment has not been followed up, and 

 that the number of eggs worked upon was not large, it has been decided to make 

 note of the results obtained, for they extend our knowledge of radiation effects. 



During the course of the experiment eggs were preserved (usually in Bouin's 

 fluid) for later cytological study. This material has been sectioned and studied 



in the Zoological Laboratory of Wabash College. 



A. R. 

 209 



