MICRODISSECTION STUDIES. 32! 



This is analogous to results obtained by injuring red blood cor- 

 puscles with a needle upon which hemoglobin escapes immediately 

 from the entire surface (Chambers, '15). 



T .g. 4 



FIG. 4. Disintegration of cytoplasm surrounding the nucleus on tearing 



the nucleus with a needle, (a) Faint hyaline sphere, a remnant of the 



destroyed nucleus, (b) Disintegrated cytoplasm. (c) Cytoplasmic surface 

 film separating disintegrated from healthy cytoplasm. 



Within the nucleus itself the immediate effect of the injury is a 

 dissolution of the nucleolus. A nuclear remnant tends to persist 

 after the injury as a hyaline sphere lying within the disintegra- 

 tion products of the cytoplasm. On being touched with the 

 needle it fades from view. 



In permanently immature eggs, such as eggs which have been 

 standing in sea water for an hour or more without maturing, the 

 disintegrative effect on the cytoplasm by injuring the nucleus tends 

 to be much more restricted, and the nuclear sphere which persists 

 after the injury can be shown to possess a morphologically definite 

 membrane. Such a sphere is easily dissected out of the egg. Fre- 

 quently, when the germinal vesicle lies close to the periphery of the 

 egg, the disintegration of the cytoplasm quickly reaches the surface. 

 With the formation of a surface film over the healthy cytoplasm 

 the disintegrative area lies in a deep bay on one side of the egg. 

 This hollow is slowly obliterated as the semi-fluid substance of the 

 egg strives to assume a spherical shape. In this way the disinte- 

 grated material is forced out of the egg together with the persisting 

 nuclear sphere. This nuclear sphere persists for some time in the 

 sea water. It can be deformed by means of the needle and, on 



