EFFECTS OF INJURY UPON SPERM. 223 



increase of size. This growth is probably due to an increase in 

 water content and gives the animals a dropsical appearance. 

 25 per cent, were as well developed as the control animals. The 

 remaining 25 per cent, were in various stages from the trocho- 

 phore to the formation of the second set of larval setae. Some 

 of them seemed to be normal in every way except that their 

 development was retarded. Others were less active. A small 

 number, perhaps 5 per cent., seemed to be as far along as the 

 controls but had no setae or were deficient in some other way. 

 Most of these died within a few hours. The controls developed 

 in a normal manner. The uninseminated controls showed no 

 development beyond the formation of jelly in about 0.3 per cent. 

 In all the cultures of the above experiment the conditions were 

 made as good as possible by changing the water, removing dead 

 eggs, etc. 



Without attempting to give other definite records, I may 

 summarize briefly the different types of effect observed in the 

 series of experiments using heat as a means of altering the sperm 

 cells. 



(a) In some cases all of the jelly did not form and the peripheral 

 alveoli of the egg were not entirely emptied. This occurred in 

 from a trace to nearly 10 per cent, of the eggs in the experimental 

 cultures. Some eggs formed a mere trace of jelly, some formed 

 about half of the normal quantity, and some had nearly as much 

 as normal. The different cases observed gave the impression 

 that a larger stimulus caused a greater jelly formation. It 

 seemed as though a sperm might in some way give only enough 

 impulse to cause a part of the alveoli to be emptied, possibly due 

 to a brief attachment to the egg. However no such egg was ever 

 followed long enough to determine the cause of this partial jelly 

 formation. 



(b) After the jelly is completely extruded and the polar bodies 

 have been formed, cells are commonly found in which no further 

 development takes place. A few r eggs do this in many unin- 

 seminated controls but there is no comparison in the frequency 

 with which they may be found. In some experiments special 

 care was taken to avoid mechanical agitation since violent 

 mechanical stimuli may produce this effect. Yet the same 



