108 CHARLES PACKARD 



gone still further. Judging from the size of the chromosomes, 

 it seems probable that they have split, fourteen daughter chromo- 

 somes going to each pole; but the number could not be exactly 

 determined. The chromatin in this case is perfectly normal. 

 In the instances mentioned, and in many others that have been 

 observed, it is apparent that the plane of one spindle does not 

 coincide with that of the other or with the first normal cleavage 

 plane. 



Occasionally, when the nuclei fail to fuse, the astral systems do 

 not develop, or, if they do, reman only a short time. The chrom- 

 atin in such cases degenerates, forming irregular, granular masses 

 which lie free in the protoplasm (fig. 28). One germ nucleus has 

 evidently degenerated faster than the other and its chromatin has 

 become much scattered and takes the hemetoxylin stain very 

 lightly. 



When the fusion of the nuclei occurs the process appears to be 

 normal. Abnormalities appear when division begins. As a rule 

 the chromatin shows few signs of injury, but the astral systems 

 are abnormal. Very commonly a tri-polar figure arises (fig. 29). 

 The asters are normal in appearance and the centrosomes are 

 normal. The chromosomes are very irregularly arranged, as 

 would be expected. But each one is well formed, showing no 

 evidence of degeneration. 



Frequently, however, the chromatin displays undoubted signs 

 of injury, as shown in figure 30. Not only are the chromosomes 

 indistinguishable but some of the strands are now broken up into 

 minute granules. There are all gradations between such a con- 

 dition and a normal figure of which there are very few in the 

 material. 



The effect, then, of the radium on fertilized eggs is much more 

 marked than that on the unfertilized eggs. This accords with 

 the results of O. and P. Hertwig, who found that the embryo frogs 

 arising from radiated fertilized eggs showed more marked abnor- 

 malities than those in the other series. The effect on the chrom- 

 atin are similar in some respects to those described by P. Hertwig 

 in the egg of Ascaris. It is evident, however, that the protoplas- 

 mic activities of the eggs of Nereis are almost equally affected 



