Development, and Structure of the Vegetable Cell. 187 
ture agreeing with the contour of the epidermic cells, such as 
indeed is possessed by the outermost coat of the epidermis be- 
longing to the epidermic layers, characterized by Mohl as 
cuticular layers.” 
If, however, the homogeneous cuticle, which, when old, may 
be slightly granular or striated, but which exhibits no cellular 
structure, is to be regarded as derived from the first excretion- 
layer of the first cell, we must ascribe to this first exeretion- 
layer the property of appropriating material out of its vicinity ; 
and as it cannot anywhere find materials ready prepared so as 
to add them to its substance by apposition in the fashion of in- 
organic growth, we shall further have to attribute to it the pro- 
perty of preparing the necessary. materials for itself from hetero- 
geneous matters by virtue of the chemical affinity inherent in 
its own substance. 
To this first excretion-layer of the first cell we must thus 
ascribe the faculties which ought essentially to belong only to 
the interior cell, to which it is indebted for its existence. It 
must possess in itself the properties of the assimilating mem- 
brane; it must be, not a mechanically excreted educt of the 
exuded cell-juice, but a portion of an organized structure, the 
membrane of an independent cell, within which the enclosed 
cells have been produced. 
With this view the results of the investigation of the develop- 
mental history of this structure published by me in 1848 (Bot. 
Zeitung) perfectly agree. 
I ascertained then, and can repeat the experiment with faci- 
lity at any time, that by means of endosmotic fluids (such as 
dilute mineral acids, solution of sugar, &c.) a delicate structure- 
less membrane may be detached from the young embryo in its 
different stages of development in the embryo-sac: the youngest 
state of this membrane is consequently the membrane of the 
germinal cell; and it may be demonstrated by the same means 
to be the outermost coat of all still cambial organs of the plant 
in course of development. 
The objection that a cell cannot so far enlarge itself as to 
overspread an entire plant, originating from the idea of the 
growth of the cell-membrane by accretion, is consequently not 
applicable; for the cell-membrane, and more particularly the 
cuticle, as already said, cannot increase itself by accretion, the 
material of which it is composed not being found in solution in 
its vicinity. 
An independent growth of the cuticle, im many cases quite 
unconnected with the adjoining cell-wall, may be recognized 
with certainty in the examples referred to at page 423, vol. xiii. 
and represented in Plate VI. figure 45. 
