EFFECTS OF INJURY UPON SPERM. 221 



Particular care was taken to insure the perfect cleanliness of all 

 pipettes. None of the liquid of the test tube was allowed to 

 splash upon the sides of the tube so as to be above the level of 

 the water in the bath. A large number of dishes of eggs were 

 made ready and one or more of these were inseminated every 

 minute until either all the sperms had been used up or the dishes 

 of eggs had all been inseminated. In this way there were usually 

 obtained one or more dishes of eggs which were inseminated 

 at the critical time which occurred from 7 to 20 minutes after 

 the sperm cells were placed in the warm bath. The variation in 

 time is probably due to fluctuations in the temperature of the 

 bath, small though they may be. This is borne out by some 

 experiments in which slightly higher temperatures were used 

 and in which the critical time came much earlier, so early in 

 fact that it was difficult to catch the sperm cells at just the proper 

 stage for use. 



Since it proved to be very difficult to determine in advance 

 which culture would be the best for study, the preservation of a 

 long series from the best -cultures is largely a matter of chance. 

 But by preserving a large number of series for cytological 

 examination, a few have been obtained which are satisfactory 

 for study. The others, although they show essentially the same 

 features, contain so many eggs which develop normally that the 

 study of the affected eggs is very time consuming. 



In all, 23 experiments, involving several hundreds of cultures, 

 were made by this method. Since the earlier work was carried 

 out in a different manner, which gave me records of the course of 

 development of the experimental cultures but no continuous 

 series of preserved samples, the primary purpose of this set of 

 experiments was to obtain material for cytological work. Ac- 

 cordingly the records of these experiments are not as full as 

 might be desired in the case of any one experiment. 



To illustrate the method of procedure the record of experiment 

 65 of July 4, 1912 is given. The eggs were removed from the 

 female at 1:39 P.M. Sperm cells removed from male at 1:40 

 P.M. Sperm placed in bath at 1:47 P.M. Temperature of 

 bath at end of successive minutes (read from centigrade ther- 

 mometer in test tube) 43; 44; 43.4; 43; 44; 44; 43.8; 43.3; 



