BASIS or THE CELL THEOllY. 281 



external chemically differentiated membrane, so much the more 

 certain does it appear to h'lm that at the period when the cells, 

 still as a whole, are mnltiplying by division, no such chemi- 

 cally differentiated membrane exists. A cell, therefore, ac- 

 cording to him would, be " a mass of protoplasm contaiiiiny a 

 nucleus in its interior." A muscle-corpuscle, therefore, 

 although in the normal condition it has no vestige of a wall, 

 nor even any definite outline might in this sense not only 

 exist, but might also properly be regarded as a cell. 



With respect to all this, I can only say that I am unable 

 to find a shadow of either reason or fact which can cast doubt 

 upon what I have formerly stated on this subject, and which 

 has not, in my work been submitted to the strictest examination. 

 To fully establish this, I should be compelled to cite the entire 

 chapter in my book ; but for the benefit of those who may 

 not have it at hand, I will quote only a single passage to 

 show the cautious reserve with which I accepted the results 

 of my own observation. After describing the formation of 

 the egg-celi-membrane on the surface of the zooplasm (proto- 

 plasm of the egg cell) after impregnation, as well as its 

 progressive action in the formation of the segments as they 

 were multiplied by division, I proceed to say (pp. 173, 174) : 

 " we have seen (p. 136) that the cell membrane, distended 

 with water, is raised up sometimes in a vesicular form, and 

 sometimes in that of a solid spongy substance. These pheno- 

 mena may be explained by supposing that the membrane 

 of the inner cells just as little as the egg-cell-membrane 

 itself is interiorly independent of the protoplasm, but that 

 it is inseparable from it, being attached by the lax connective 

 medium by which the germ corpuscles are held together, and 

 possessing similar chemical properties to those of the mem- 

 brane itself. To this circumstance may be referred the doubts 

 of those who deny in general the existence of a membrane 

 in the segment cells, and recognise in them merely a 

 '' sarcode-like " connective medium derived from the proto- 

 plasm. To all these notions is opposed the circumstance 

 that, every kind of chemical reagent having an immediate 

 and energetic action during life, corrosive sublimate, solu- 

 tion of nitrate of silver, vitriol, sulphuric acid, chromic 

 acid, alcohol), harden the thin smooth envelope of all the 

 cells in the form of a separable membrane, and that many 

 phenomena (p. 135, section 15) even indicate the presence of 

 a special envelope or agglutination of the protoplasm, Avhich 

 thence derives a definite border, even when the distended 

 cell membrane cannot afford it. The question may, never- 

 theless, arise, whether, in any one case and to what extent in 



VOL. II. NEW SEU. U 



