EFFECTS OF INJURY UPON SPERM. 227 



pear, though a few individuals nearly always succeeded in reach- 

 ing the later stages. If the sperm cells were not injured so much, 

 the earlier stages were comparatively free from abnormalities 

 and those of the later stages appeared, chiefly the permanent 

 trochophores, the malformed bodies and the lack of setae. 



In these experiments, as in those to be described later, the 

 number of eggs fertilized is inversely proportional to the strength 

 and duration of action of the injurious agent, provided the pro- 

 portions of eggs and sperm are constant. The degree of abnor- 

 mality and the per cent, of abnormal forms is directly propor- 

 tional to the strength and duration of action of the agent used. 

 These statements, of course, are not to be taken as more than an 

 approximation. No effort has been made to reduce the results 

 to the form of an exact law r . However the results of the series 

 are consistent and conform nicely to the above generalizations. 



2. Delay. Striking results were obtained by keeping the sperm 

 cells for some time before they were used for insemination. 

 Naturally the extreme time which may elapse before the sperm 

 cells become incapable of influencing the eggs varies greatly 

 with the temperature, with bacterial conditions, and, I suspect, 

 with the general vitality of the cells. The complexity of the 

 conditions makes it extremely difficult to completely duplicate 

 the results of any particular experiment. Oftentimes it happens 

 that the results in experimental cultures are nearly normal and 

 again development may not appear at all. Yet the results all 

 seem to be consistent, the differences being in degree only. As 

 in the set of experiments described under the head of heat, the 

 abnormal types are undoubtedly due to certain degrees of injury 

 to the sperm cells. The possibility of the results being due to 

 toxic substances produced by bacterial action or sperm metab- 

 olism during the period of delay, and introduced into the egg 

 cultures at the time of insemination, seems to be rather remote. 

 In order to minimize any such effect, the water was changed on 

 the egg cultures several times shortly after insemination. 



One of the several extreme cases of effect upon early develop- 

 ment is found in experiment 34 of July 15, 1911. The uninsemi- 

 nated control remained unchanged. The fertilized control was 

 inseminated at 2:11 P.M. At 3:15 P.M. the first cleavage was 



