22 Mr. G. H. K. Thwaitcs on the Cell-Membrane of Plants. 



membrane is quite a subordinate part of the living structure ; 

 that its functions are of a purely physical character; that its 

 principal office is to protect, locate or isolate the matter it con- 

 tains j and that any vitality it possesses is derived from the pre- 

 sence within it of its endochrome. There are, however, a few 

 phenomena which at first sight would appear to militate against 

 the opinion I have advanced ; I mean the contractility of certain 

 membranes, and the movement of ciliary appendages belonging 

 to others. It is very certain, that during the vital processes which 

 are going on in the interior of the cell, considerable chemical 

 changes are taking place ; and these must of necessity give rise 

 to an elimination of electrical currents. The presence of such 

 currents would, I think, be sufficient to account for the rhythmical 

 movement of cilia, as well as for the contraction of membranes of 

 certain mechanical structure. 



I would ask whether these electrical currents may not give rise 

 to the formation of the mucus surrounding the cell, and deter- 

 mine its character and extent ; whether, too, the production of 

 cell-membrane may not occur under a similar influence; and 

 whether this would not be the easiest solution of the problem of 

 how the cell is increased in size ? viz. that a formation of cell- 

 membrane takes place within the range of these currents, whilst 

 absorption occurs within or without it. On this principle, too, we 

 can better understand the process of the fissiparous division of 

 cells ; the endochrome becoming divided into two portions, two 

 centres of electrical force are originated, and each of these giving 

 rise to a set of currents, two cell-membranes are produced instead 

 of the original one. The frequent occurrence of nests of regular 

 crystals (not sand) in the substance of the mucous envelopes of 

 such freshwater genera as Batrachospermum, Chcetophora and 

 Monormia, would seem to afford positive proof that electrical cur- 

 rents exist there. 



These views, if correct, would of course apply to animal as well 

 as vegetable organisms, and we should be under the necessity of 

 considering the entire membranous or solid portion of the animal 

 as of a subordinate character to the fluids contained in its cells, 

 and merely as an instrument acting in prompt obedience and con- 

 formity to the changes taking place in these fluids. 



But treating the subject of the functions of the cell-membrane 

 in a chemical point of view, we know that considerable che- 

 mical changes are taking place during the processes of assimila- 

 tion, secretion, elaboration, &c. ; that these are essentially che- 

 mical phenomena. Are we to look to an organ of such a low 

 chemical constitution as cell-membrane as likely to give origin 

 or the initiative to these important changes ? I cannot believe 

 such can be the fact, but that the organ or substance which gives 



