32O WILLIAM SEIFRIZ. 



the kind of membrane formed, is dependent upon the physiologi- 

 cal state of the protoplasm, which, in a sense, means that the 

 ultimate control lies within the cell ; though, of course, not beyond 

 the purely physical and chemical properties of the living substance. 



The prevailing idea of a cell wall is that it is a dead structure 

 and, therefore, incapable of change or response to environment. 

 This is probably true of the cellulose walls of older cells, but not 

 of the distensible, glutinous membranes and egg-walls here dis- 

 cussed nor of the cell-walls of meristematic tissues in general. 

 The suggestion that the wall of a degenerating ovum may and 

 does undergo, with the egg-protoplasm, a change which permits 

 either its going into solution or its ready rupture by internal 

 osmotic pressure, is not without experimental support. Proto- 

 plasmic membranes are an intimate part of the living substance 

 and susceptible to the same changes in environment. (Baylissi 

 1916, p. 115.) 



Normal protoplasm, in all cases studied by the writer, does 

 not mix with water. This declaration is contrary to that of 

 Chambers (19170, p. 2). If the decision is to rest on evidence 

 gained solely from microdissection then miscibility of the proto- 

 plasm is a consequence of degeneration. Chambers's statement* 

 however, rests not only on microdissection but on the introduc- 

 tion of water into the cell by the mercury injection method as well. 

 Miscibility precludes the presence of a membrane. Normal 

 protoplasm is always capable of membrane formation. There- 

 fore, normal protoplasm can at no time be miscible. The dis- 

 section of a great many eggs supports this conclusion. 



To the highest powers of the microscope, with ordinary illumi- 

 nation, protoplasm is a homogeneous, structureless solution. 

 Its colloidal nature becomes evident on using the dark ground 

 illuminator. Protoplasm is probably an emulsoid hydrosol, 

 i. e., a colloid in which both phases are liquid, one of them the 

 dispersion medium being water. 



Any definite statement on the ultimate structure of proto- 

 plasm must be expressed in physicochemical terms, and based 

 upon observations made with the ultra-microscope. The be- 

 havior of protoplasm under dissection, however, throws consid- 

 erable light on the gross structure of the cell contents. In dis- 



