6 G. L. KITE. 



tions the nuclear membrane is impermeable to vital stains. This 

 structure is a concentrated tough gel of relatively high viscosity 

 and is not to be confused with hypothetical surface or vacuolar 

 plasmatic membranes. If the concentration of a suitable vital 

 stain be raised considerably or the nucleus be dissected out, 

 staining occurs. 



Puncture of the walls and probably the cytoplasm of various 

 types of plant cells has given unanticipated results. All the 

 more common acid dyes enter the cells of such plants as Spiro- 

 gyra, Elodea, Hydrodictyon, different root-hairs, and the paren- 

 chyma cells of Tradescantia, following an extremely small 

 puncture. Puncture of the walls of slightly plasmolyzed Spiro- 

 gyra and Elodea cells is followed by protoplasmic staining when 

 acid dyes are added. On the other hand, puncture of thoroughly 

 plasmolyzed Spirogyra cells is followed at most by a slight surface 

 staining, of the shrunken and concentrated cytoplasm, by the 

 same acid dyes. 



During plasmolysis of Spirogyra a large amount of mucilag- 

 inous material is poured out of its wall, and, as a result, this 

 structure loses much of its rigidity, becomes softer, and permeable 

 to many acid dyes. This striking change can be demonstrated 

 by vital stains, dissection of the wall of thoroughly plasmolyzed 

 cells, and by staining cells immediately after recovery from 

 thorough plasmolysis. 



A very small cut in the wall of a manubrial cell of Chara gives 

 even with trypan blue and trypan red only a local staining of 

 the cytoplasm, which slowly spreads. 



THE DISSECTION OF CELLS. 



The chief cells that have formed the material for this study 

 have been dissected by the use of adequate methods, and their 

 physical properties, such as rigidity, viscosity, glutinicity, 

 elasticity, tenacity, and colloidal state, have been determined. 

 Although these data are too extensive to be given here, they form 

 a part of the basis of my conclusions. 



CONCLUSIONS. 



i. The structural components of protoplasm vary greatly in 

 their permeability to water, dyes, and crystalloids. 



