112 CHARLES PACKARD 



asters are developed from the egg protoplasm, it is evident from 

 their peculiar behavior that the latter substance has been injured. 

 The chromatin also is affected, as is shown in the cases of irregu- 

 lar formation of the maturation chromosomes, and in its be- 

 havior in the nuclear vesicles. But the many cases of perfect 

 formation of the chromosomes and their normal splitting, even in 

 the minutest details, indicate that the effect of the radiations on 

 the chromatin has not been profound. 



DISCUSSION 



The work of G. Hertwig and others points to the conclusion 

 that the chromatic elements of the nucleus are the only parts of 

 the cell which are disturbed by the radium radiations. The con- 

 clusion that no other constituents are affected has been drawn 

 from the fact that the usual methods of technique do not reveal 

 any chemical changes in the protoplasm. Such a criterion is, 

 in many cases the best we have, but it is evident that staining 

 will not reveal all of the cell constituents which are known to be 

 present, which, like enzymes, operate on the protoplasm of the 

 cell, changing its chemical constitution; nor will it give evidence 

 of the nature of such changes. 



There are no visible changes in the radiated sperm — a fact that 

 led Hertwig to believe that the protoplasm was uninjured. But I 

 believe that in the sperm of Nereis there is evidence that a proto- 

 plasmic change has taken place. This change becomes apparent 

 through the activities of the egg in the early stages of fertiliza- 

 tion — activities which are incited by the stimulus of the sperm 

 itself. In the first place, when the sperm becomes implanted in 

 the egg membrane it injects into the egg a coagulating substance 

 which, according to Lillie, changes the protoplasm so that it takes 

 a fairly deep stain with hematoxylin. This staining reaction is 

 frequently lacking. It cannot be said that the egg protoplasm 

 has been changed since all of the eggs used in the experiment were 

 normal. Therefore it may be inferred that the protoplasmic 

 elements in the sperm have been modified. 



