EFFECTS OF INJURY UPON SPERM. 233 



of acid affected the sperm cells so much that the eggs inseminated 

 by the sperm cells so treated were unchanged or merely formed 

 jelly and polar bodies without segmenting. 



An attempt was made with weak NaOH solution to neutralize 

 the acid in which the sperm cells were placed before insemination 

 but this process so often destroyed the life of the sperm cells that 

 it was useless for control purposes. However, the controls 

 used seemed to be sufficient to show that the cause of the altered 

 development does not lie in the presence of the acid in the experi- 

 mental cultures of eggs. 



/. Cold. Freezing the sperm was effected by placing them in 

 sea water in a test tube and imbedding the tube in a mixture 

 of powdered ice and salt. - 8 C. killed the sperm. - 2.2 C. 

 gave a mush}' ice in the test tube. The sperm cells were not 

 killed but caused a normal cleavage in the eggs. From 5 to 10 

 per cent, of the larvae were abnormal. A very few scattering 

 abnormalities of all the kinds previously mentioned were ob- 

 served. 1.6 C. did not seem to affect the sperm cells enough 

 to alter the egg development. 



Since low temperatures are very difficult to handle by means 

 of the crude methods employed extensive experiments were 

 not carried out along this line. Refrigeration at a temperature 

 considerably above freezing for longer periods was also used as a 

 possible source of injury to the sperm cells. Since the effects 

 produced are probably due as much to the delay as to the cold 

 these experiments have been mentioned under a previous heading. 



B. Upon Arbacia. 



In July, 1911, a series of 18 experiments involving about 200 

 cultures was carried out, using the sexual products of the common 

 sea urchin, Arbacia pimctulata. Along with some other investi- 

 gators I had considerable trouble at that particular time in 

 getting control experiments to develop in a normal manner. 

 Accordingly the work w r as not carried as far as it seemed desir- 

 able at that time. Although the results were perfectly convinc- 

 ing to one who could see the living material, the small percentage 

 of abnormality in the controls might cause some to question the 

 value of the published data. I will, however, give a brief survey 



