MOHL ON THE STRUCTURE OF THE VEGETABLE CELL. 101 
ordial utricle maintaining its perfect integrity in the Phanero- 
gamia, in the cells of the leaves containing chlorophylle granules, 
and in the outer green cells of the bark, replacing in a physio- 
logical point of view the leaves of the fleshy Huphordie ; that 
moreover we observe the same in the Algz, the individual cells 
of which exist in a great degree independent of one another. 
Ought we not then to conclude that the primordial utricle takes 
a part in the assimilation of the crude nutritive juices, as well 
as in the origination of the cell? But enough of conjectures as 
to the functions of an organ whose very existence has yet to be 
admitted by other observers ! 
Postscript.—I had already written the above when I read M. 
Karsten’s treatise De Cella Vitali, from an earlier study of which 
I had been hindered by accidental circumstances. I perceived 
from it that its author was also acquainted with the structure 
which I have called the primordial utricle, that he too accom- 
plished its separation from the cell-wall by the employment of 
spirit of wine, but that he had advanced a theory of its function 
directly opposed to that above given, since he ascribes to it an 
origin subsequent to that of the proper cellular membrane, and 
holds it to be a secondary cell, formed in the cellular cavity. 
There consequently existed a contradiction to my observations, 
even before they were published: this will not matter, but will 
rather be an inducement for some one else to devote himself to 
the investigation of this subject. Should my view prove to be 
untenable, it may be placed in the great chapter of phytotomical 
errors, if only the truth comes forth in the contest. I will only 
observe in reference to the representation which Karsten has 
given of the primordial utricle, that he was indeed acquainted 
with it, but that nevertheless he confounded it with the second- 
ary layers of the cellular membrane. These two membranes 
differ from each other as much as any two things can do which 
have not the slightest connexion with one another. 
2. The Cell-membrane. 
If we now pass from the temporary structure of the primor- 
dial utricle to the permanent formation of the cellular membrane, 
we find the latter always to be composed of at least two layers, 
an outer, which I regard as the oldest cellular membrane, and 
an inner, which I consider a secondary deposit. Hartig takes 
not only a different view in reference to the order of their ori- 
