Wenham, on the Vegetable Cell, 
63 
mentary cell-cavities appearing spontaneously throughout the 
mass at the same time, and increasing independently of each 
other ; in every one the inner lining of each space in the 
formative protoplasm becoming hardened into a membranous 
layer, which may be readily proved, as the unconnected cell- 
sacs can be washed out of the containing plasma and isolated. 
The " vacuoles " are rather apt to take their rise from the 
larger particles contained in the plasma, but I believe that 
this is only a mechanical and not a vital condition, for it is 
equally certain that a large number of them form themselves 
apparently without any starting point whatever. In Anacharis, 
and many other plants, these cells, in the first stage of their 
existence, are simple membranous sacs, containing nothing 
else but a limpid, watery fluid, and a few very minute granu- 
lar bodies adhering to the cell-wall — and here is a point at 
issue. It is maintained that cells, even in their very earliest 
stage, contain an active nitrogenous layer lining the interior 
of their cavities — the so-termed " primordial utricle." My 
own observations cannot confirm this ; and, indeed, reasoning 
independently of the evidence of eye-sight, it seems an 
anomaly to expect a detached portion of a material to be 
enveloped in a cavity of its own substance, before any limitary 
membrane is completely formed to prevent their coalescence. 
Neither can it be set down as a general rule, that new cells 
are commenced singly around a collection of solid contents, 
for " vacuoles " are to be seen of the minutest size, which are 
afterwards expanded, so as to become perfect cells in all 
respects ; unless in this case it is assumed that the formation 
takes place around invisible contents. 
As I have before stated, it is not until the membrane of the 
sac is completely formed, that protoplasm is found within the 
cell ; this is rapidly followed by the deposit of internal 
film of protoplasm, in a free state ; if this is scraped ofif it will be found 
to contain transitional cambium cells, dotted ducts, &c., in all stages of 
development. The formative plasma is mostly deposited in the form of 
strips, in the grooved surfaces of the bark and wood, and there rapidly 
resolves itself into a row of cells, or hardens into a fibre, according to the 
influences of local conditions, or the size of the matrix. These cells are 
not formed by the division of older ones, but arise directly from the 
simultaneous cellulation of the formative plasma, in the manner that I 
have explained in other instances. 
From the light colour of the substance it is a difficult matter to investi- 
gate the young cellular deposit, as an opaque object ; but after the surface 
has dried, an impression may be taken with black sealing-wax, which will 
also sometimes bring away some of the young cells in course of formation, 
and afford a more satisfactory view of the cell stages and arrangement, 
using a Leiberkuhn for illumination. 
