1884.] Mr W. Gardiner, On the constitution of the cell-wall, &c. 87 



February 11, 1884. 

 Mr Glaisher, President, in the chair. 



The following communications were made : 



(1) On the constitution of the Cell-wall and Middle Lamella. 

 By Walter Gardiner, B.A. 



If we accept the view of Schmitz 1 and Strasburger 2 as to the 

 first formation of the cell- wall, we must regard the cell-plate which 

 appears as a delicate septum between the two dividing nuclei, and 

 at the equator of the achromatin spindle, as consisting of a number 

 of microsomes imbedded in a protoplasmic matrix 3 . 



The cell-wall which is subsequently formed, is the expression 

 of a chemical change having taken place in the structure, in con- 

 sequence of which cellulose appears as one of the principal bye- 

 products: that is to say: that from the breaking down of a complex 

 proteid, a carbohydrate has been produced. 



The succeeding thickening of this primitive cellulose mem- 

 brane 4 , is brought about in a manner quite similar to that which 

 attended its first formation, viz. by the repeated apposition upon 

 it, of fresh sheets of microsome-laden protoplasm, which are suc- 

 cessively deposited and converted into layers of cellulose, except 

 that in the case of the secondary thickening, the microsomes are 

 deposited by the general parietal protoplasm, and are not conveyed 

 in the special fibrils of the achromatin spindle, which disappear 

 with the formation of the primary wall. 



Simultaneously with this thickening other phenomena usually 

 occur. In the first place owing both to chemical alteration, and 

 to pressure and tension, a distinct median layer becomes differen- 

 tiated in the hitherto homogeneous wall which separates the contents 

 of adjacent cells, so that the wall appears to be no longer common, 

 but on the contrary, each cell-wall appears to be surrounded with 

 its own cell-membrane, and, at the junction of the two is the well 

 defined layer in question, which is usually known as the middle 

 lamella. 



1 Schmitz, Sitzber. niederrhein. Ges. in Bonn, Dec. 6th, 1880. 



2 Strasburger, Bau und Wachsthum, p. 173. 



3 Were the idea borne out by observed facts, it would be simpler for the cell- 

 wall to consist simply of aggregated microsomes, which gradually coalesce into a 

 firm membrane, the microsomes being regarded as formed proteid substance, and 

 hence midway between protoplasm on the one hand and cellulose on the other. 



4 In certain instances it would appear that the primitive membrane may not 

 consist solely of cellulose, e.g. the seed of Ardisia where starch is present. The 

 statement here refers only to typical walls. 



