40 Mr G. F. Scott Elliot on Recent Researches [sess. li. 



Recent Researches in regard to the Vegetable Cell-Wall. By 

 G. F. Scott Elliot, M.A. Cantab. 



(Read 9th December 1886.) 



So long ago as 1864 Pringsheim* observed a peculiarly 

 modified layer of protoplasm lining the cell-wall in the endo- 

 sperm of Ornithogalum. He found that this layer had 

 disppeared when the cell-wall was fully formed, and he con- 

 eluded that it had been changed into cellulose. He had, 

 therefore, apparently a very clear idea of the apposition 

 theory. Von Mohlt and Nageli| attacked Pringsheim's 

 view, introducmg instead the theory of growth by intussus- 

 ception, which has since (until lately) been pretty generally 

 accepted. Schmitz,^ in 1880, reopened the question by an 

 excellent paper, in which he proved that the cell-wall 

 grows by successive deposition of lamellae, each lamella 

 being originally a layer of protoplasm, and he also gave an 

 explanation of the growth in surface of the cell-wall (Nageli's 

 main objection to the apposition theory), which has since 

 been generally adopted. Each lamella, according to Schmitz, 

 is stretched by the turgid condition of the cell, and a new 

 lamella, being laid down over the older one, renders this 

 distension permanent ; and it is afterwards distended in 

 turn by younger lamelhe. He also noticed that the layer 

 of protoplasm next the cell-wall, or " inncnhaut" (lamella in 

 course of formation) contained many small granules, or 

 microsomes, which were intensely coloured by hematoxylin. 

 Schmitz considered, however, that it was possible, or even 

 probable in certain cases, that the cell-wall continued to grow 

 internally after its formation, though not in the way Nageli 

 supposed. Strasburger,j| in 1882, l)rought forward a very large 

 number of observations supporting Schmitz's views, which 

 he also extended and developed. He considered, in parti- 

 cular, that the " apposition" mode of growth holds universally, 

 growth by any kind of intussusception never taking place, but 

 this view, from what follows, appears at least questionable. 



I liave brought forward the present paper in con- 



* Pringsheim, Ueher d. liau. u. Bildunfj. d. FJlanzenzclle, 1854. 

 t Von Mohl, Hot. Zeitung, 1855. X Niigeli, 1858 ; see Das Mikroscop. 



§ Schmitz, Sitz. d. niederrhin. Ges. f. Naiur. u. Eeilkwnde in Bonn, 1880. 

 II Strasburgcr, B(iu. u. WachHthiim d. Zellhaute, Jena, 1882. 



