UESEAROHES ON PROTOPLASMIC CONTINUITY. 305 



told that " what has been sometimes described by authors, 

 especially in growing tissues, as ' intercellular spaces,' and 

 " middle lamellse " in the cellulose were revealed to be, in a 

 number of instances, accumulations and filaments of living 

 matter wedged in between the plant cells." Since it is impossible 

 to understand how an intercellular space (if Dr. Elsberg really 

 means space) can be an accumulation of anything, one must 

 proceed to deal with the question of the middle lamella being 

 an accumulation of living matter, &c. It is an undoubted 

 fact that the substance of the middle lamella resembles proto- 

 plasm in many of its properties. Thus, like protoplasm, it 

 resists the action of strong sulphuric acid in cases where it has 

 attained to any pronounced degree of development, and, like it 

 again, dissolves in strong potash or in Schultz's mixture ; and 

 it is very noticeable that many reagents which are used as 

 special stains for the protoplasm will also stain the middle 

 lamella. But whatever view be taken as to the nature of the 

 middle lamella and the thickened cell wall, and no matter 

 whether one accepts the intussusception theory of Nageli,^ or 

 the apposition theory of Schmitz^ and Strasburger,^ it is quite 

 certain that at the time of its first formation the cell wall is 

 essentially cellulose, and is thickened by deposits of cellulose 

 substance. If protoplasm in any way enters into the constitu- 

 tion of, or forms an integral part of, that structure which we 

 recognise as cell wall, it is, to say the least of it, hard to ima- 

 gine, even on the well-nigh exploded intussusception theory, 

 that such large quantities of protoplasm should be present, not 

 only to replace the structure which we are accustomed to regard 

 as middle lamella, and as such consisting of altered cell wall, 

 but even large areas on either side of it, in such proportion as 



' Niigeli, "Die Starkekorner." 

 Nageli and Schwendener, " Das Microscop," &c. 



2 Scbmitz, " Sitzber. d. niederrhein Ges. in Bonn," 1879 and 1880. 



3 Strasburger, "Bauund Wacbstum," Leipzig, 1882. In connection with 

 this subject, cf. also Schimper, " Ueber das Waclistum der Starkekorner," 

 'Bot. Zeit.,' 1881, 186; and Mayer, "Ueber die Structur der Starkekorner," 

 ' Bot. Zeit.,' 1881, 844. 



