254 NEIL S. DUNGAY. 



only once or twice. Although we have no direct evidence as to 

 the comparative rates of metabolism of eggs fertilized with normal 

 sperm and those fertilized with injured sperm it seems possible 

 that a difference exists. The retardation in development, the 

 higher mortality in the later stages, and the differences in photo- 

 tropic response indicate that this is likely. 



VII. SUMMARY. 



1. Nereis eggs, inseminated with sperm cells which have been 

 injured by one of several methods, may fail to develop in a 

 normal manner. 



2. In some cases the egg does not form a fertilization cone, 

 attachment granules are lacking and the sperm head is not drawn 

 into the egg but remains outside attached to the vitelline mem- 

 brane. There are two classes of such eggs, neither of which 

 segment, viz.: (a) Those which slowly undergo maturation with- 

 out forming jelly, (b) Those which form both jelly and polar 

 bodies. 



3. Those eggs in which the sperm head enters, form the first 

 cleavage spindle in an apparently normal fashion but may fail 

 to complete the division of the cytoplasm. Those which com- 

 plete this division may develop abnormalities in later stages. 



4. The eggs of Arbacia exhibit a similar series of abnormalities 

 when fertilized by weakened sperm cells. 



5. There is no indication of specificity in the action of the 

 agents used in injuring the sperm cells. 



6. These experiments demonstrate that eggs fertilized with 

 sperm cells injured by alcohol and by other means may produce 

 abnormal forms. Taken in connection with the demonstration 

 by others that the germ cells of mammals may be exposed to 

 injurious conditions this has an important bearing upon the 

 relation of alcoholism to the production of defectives. 



7. There seem to be at least two factors involved in the process 

 of fertilization. The one has to do with membrane formation 

 and certain other changes, the other with the internal stimulus. 



8. In Nereis the presence of the two germ nuclei within the 

 egg is not necessarily sufficient as an internal stimulus for normal 

 development. 



