320 



ROBERT CHAMBERS. 



apparent injury (Chambers, '17-0). If, however, the nuclear 

 membrane be torn, a very striking phenomenon occurs. The cyto- 

 plasm immediately surrounding the nucleus disintegrates and 



F/g. / 



2.50 



2.45 



FIG. i. Figures showing the extent to which the nucleus (germinal 

 vesicle) of an immature starfish egg may be indented en one or both sides 

 without rupture. On removing the needle the nucleus reverts to its original 

 spherical shape. 



FIG. 2. a, immature starfish egg cut at 2:45 P.M. into three parts; the 

 nucleus has remained intact but is laterally compressed in the middle frag- 

 ment, b, c, d, e and /, successive steps in attempt of nucleus to round up ; 

 b, 2:50 P.M.; d, 3:00 P.M.; /, 3:10 P.M. 



FIG. 3. a, partial rupture of nucleus followed by a repair of its membrane. 

 b and c, successive changes in the shape of the nucleus within the following 

 ten minutes after which time it disappeared. 



liquefies. If the rupture of the nucleus be violent, the disintegra- 

 tion of the cytoplasm spreads rapidly until the entire egg is in- 

 volved. If the rupture be slight, the disintegrative process is 

 quickly limited by a surface film which forms on the boundary 

 between the disintegrating and the surrounding healthy cytoplasm 

 (Fig. 4). This film tends to prevent any further spread of the 

 destructive process. The destruction of the cytoplasm is evidently 

 due to something which emanates from the injured nucleus. The 

 injury to the cytoplasm does not start where the nuclear membrane 

 is first torn, but from the entire surface of the injured nucleus. 



