EFFECT OF RADIUM ON FERTILIZATION 103 



and are deep in the egg. Careful search has not revealed any 

 asters or spmdle fibers. In figure 12 the spindles have formed, 

 as well as the chromosomes, but the asters are lacking. Here, 

 too, the spindle forms in the center of the egg. There are other 

 cases in which very small asters are present, with fairly normal 

 chromosomes. Occasionally figures like figure 13 occur, in which 

 the achromatic portion of the figure is normal, but the chromo- 

 somes are segmented. A more normal type is seen in figure 14. 

 The normal condition seems to be due to the fact that the alveolar 

 layer has been extruded at the periphery nearest to the spindle, 

 allowing the usual relation to obtain between the protoplasm 

 and the sea water in the egg protoplasm. 



In a majority of cases, however, the alveolar layer is extruded 

 normally. In all instances the spermatozoa may enter normally 

 or may show a characteristic abnormality, which, curiously 

 enough, is similar to a condition found in normal eggs fertilized 

 by radiated sperm. It consists in the failure of the fertilization 

 cone to stain the usual dark color. Figure 15 shows such a con- 

 dition. It will be noticed that the sperm is normally implanted 

 and has already become anchored in the substance of the cone 

 by minute attachment granules. The cone itself is transparent, 

 and traversed by a delicate achromatic network. Immediately 

 around it the protoplasm is of normal appearance. Later the 

 cone sinks into the protoplasm in the normal manner, pulling with 

 it the sperm head. The non-staining quality apparently has no 

 effect on its function. 



Lillie suggests that the normal deep stain of the cone is due to 

 a coagulating fluid injected by the sperm into the egg through the 

 perforatorium. If this is true we have another evidence that the 

 chemical reactions of the egg protoplasm, have been changed by 

 the radiation. 



The formation of the first polar body may be very abnormal, 

 but the abnormalities concern chiefly the achromatic portions of 

 the spindle. As a rule the chromatin is but slightly affected. 

 Figure 16 shows a well marked tri-aster with large centrosomes 

 which are abnormal in size. It will be noticed that the chromo- 

 somes, even in the minutest details of splitting are perfectly nor- 



