ox GROWTH AND EXTENSION' IX THE VEGETABLE KIXGDOM. 3( 



Schleiden supposes the cell-nucleus, which he calls also ci/tohhist, 

 to be formed of several smaller ones, and then says : * " When the 

 cell-nuclei are completely formed, there soon appears around them 

 a thin membrane, which is sometimes extraordinarily fine and soft, 

 sometimes thicker and tougher. This membrane soon rises in 

 the form of a bladder on one surface of the nucleus, then gra- 

 dually stretches till the nucleus only occupies a very small por- 

 tion of the cell-wall." There does, it is true, soon form a mem- 

 brane round the cell-nucleus, but outside of this is formed another, 

 which is the proper outer co;iting (or wall) of the cell, and with 

 nitric acid the inner membrane which incloses the nucleus may 

 be easily separated from it, and plainly seen : all these mem- 

 branes are formed of the mucilaginous fluid in which the granules 

 are found, as may be seen in drying it, — therefore membranes 

 over membranes. On the multiplication of cells, Schleiden 

 had already, in Miiller's ' Archiv der Physiologic,' 1838, p. 137, 

 announced the following opinion : " Tiie cytoblasts are formed 

 inside a cell, in a mass of mucilaginous granules, and the young 

 cells lie also free in the parent cell, and as they arrange tliem- 

 selves one against the other assume a polyhedral form. At a 

 later period the parent cell is absorbed." In the book quoted 

 below, he adduces (p. 317) as proofs in support of this opinion, 

 the protococcus, the double spores of lichens, the utricles of 

 pezizas, the spore-cells in tlieir parent cells in ferns and equiseta ; 

 and in phaenogamous plants the embryo sac and the pollen ; and 

 at last he adds, "in the point of the bud, in the cambium, we 

 may not unfrequently succeed in seeing the newly-formed cells 

 within the parent cell ; almost all hair-formations show the 

 process well." As to the latter cases, we may call the cell- 

 nucleus a cell, but it never comes out, nor is it developed into 

 a separate cell, it only spreads in the form of a granular mass. 

 We may also call cells such organs of generation as Schleiden 

 adduces, as inclosed in membranous envelopes ; but to predict of 

 all cells what has been observed of these, would be, as tlie old 

 philosophers termed it, a sophism, de genere in genus. 



That every cell is of itself a distinct organ I have long since, 

 and as I believe the first, maintained. f The axiom has since 

 become the common property of the science. The function of 

 ordinary cells is to work on the sap contained in them ; for one 

 often sees cells filled with red sap in the midst of others con- 

 taining green stuff or chlorophyll. Besides these coloured saps 



* ' Elements of Scientific Botany,' 3rd edition, vol. i. p. 209. 



\ See Romer's ' Archiv der Botanik,' vol. iii. part iii. p. 439. Leipzig, 

 1805. " Quaevis cellula sistit organon peculiare, nullo hiatu nee poris con- 

 spicuis prreditum in vicina organa transeuntibus. Conrpicies nou raro cel- 

 lulam rubro tinctam colore inter reliquas virides." 



