25O NEIL S. DUNGAY. 



tions for life and growth, other abnormalities would occur in 

 later stages, but since experimental cultures which are apparently 

 normal in the earlier stages frequently develop abnormalities in 

 the larval condition, it is very probable that other changes 

 would come to the surface in still later stages. In the Nereis 

 experiments there can be no doubt as to the cause of the abnor- 

 malities observed. The controls, using the sexual products from 

 the same animals, exclude the possibility of abnormalities being 

 present in the lines used. The very large numbers handled 

 demonstrate that the results are not due to the chance out- 

 cropping of hidden defects. The series composed of Arbacia 

 material, if standing by itself, might be questioned. But the 

 general type of results is so similar to that obtained by Bardeen, 

 the Hertwigs, Stockard, and myself on other forms that there can 

 be no question as to their applicability. 



The lack of specificity in the action of the agents used is 

 remarkable. At first thought it seems strange that acid, alkali, 

 alcohol, heat, delay, and other means should produce similar 

 results. It is clear that the action must be much the same in 

 all the cases which I have recorded as well as in those recorded 

 by the authors cited. At present we can neither assign a 

 definite reason for the lack of specificity in the results nor tell how 

 the abnormalities are produced. I can only suggest that the 

 sperm cells are affected in such a manner that their vitality is 

 lessened, or in other words, their rate of metabolism is lowered. 

 It is known that the rate of metabolism in the normally fertilized 

 egg rises rapidly after the time of fertilization and continues to 

 rise for some time. Child ('n) has shown that in the regulation* 

 of pieces of Planaria the type of structure formed may be 

 definitely controlled through changes in the rate of metabolism 

 produced by means of low temperature, anaesthetics, carbon 

 dioxide, etc. He finds that, in a general way, regions of normally 

 low rate, such as posterior regions, are most affected. Any 

 particular process of morphogenesis seems to require a certain 

 minimal rate of metabolism for its normal completion. It is 

 possible that we are dealing with a similar case. The injured 

 sperm cell may be unable in some cases to give to the egg a 

 sufficient stimulus to raise the rate of metabolism to a point 



