EFFECTS OF INJURY UPON SPERM. 24! 



completely confirms the observations made upon the living 

 material. The sperm cell becomes attached to the vitelline 

 membrane, the processes of maturation and jelly formation follow 

 in a normal manner, and the animal pole of the egg becomes free 

 from yolk. But no fertilization cone is formed and no attach- 

 ment granules appear at the end of the perforatorium (Fig. 4). 

 The egg protoplasm just beneath the attached sperm shows no 

 more change than that at any other part of the egg. The per- 

 foratorium, which in cases of normal attachment becomes wider 

 and more easily seen (Fig. 5), remains as a very delicate process 

 which cannot be followed beyond the vitelline membrane. Large 

 granules, which stain deeply in the iron heematoxylin, soon 

 appear in large numbers in the peripheral parts of the egg and 

 also around the egg nucleus. In later stages the sperm head 

 becomes larger and somewhat less dense and often disappears 

 entirely. This is presumably due to secretions which are thrown 

 off from the egg, as has been demonstrated by F. R. Lillie ('12). 



No evidence of the presence of a sperm within the egg can be 

 found. At the close of the second maturation period the egg 

 chromosomal vesicles begin to swell and may unite with each 

 other to a greater or less extent (Fig. 3). Cytoplasmic parts of 

 the mitotic figure never appear although there are sometimes 

 traces of chromosome formation within the vesicles in the 

 earlier stages (Fig. 6). In some cases the vesicles separate and 

 scatter through the cytoplasm where they may dissolve and leave 

 behind a number of deeply staining chromatic nucleoli. More 

 often the vesicles remain in place and break down into a mass of 

 poorly staining debris (Fig. 7) in which, in the earlier stages, 

 chromosome-like forms may be visible. Two or three hours 

 after insemination the cytoplasm frequently begins to bud off 

 small pieces filled with deeply staining granules. This usually 

 appears first. near the equator. Later the whole cell may break 

 up into parts which more or less resemble blastomeres, although 

 close examination in the living state reveals their nature. In 

 sections it is easily seen that the parts do not possess nuclei. 



It is clear that the injured sperm has given the first stimulus 

 of fertilization. But, although the initial stages have been pro- 

 duced, the effects necessary for further development have not 



