100 MOHL ON THE STRUCTURE OF THE VEGETABLE CELL. 
part of those still little known, constantly-changing formations 
(Gebilde) which are found accompanying the nucleus in young 
cells. In spite of this I believe that its substantiality as a di- 
stinct organ is beyond doubt, since it is not only present in all 
young cells as a distinctly marked, perfect membrane, but in 
many lower plants, as in the Confervee, it occurs isolated, without 
nucleus, and is present as a perfectly closed cell in certain organs 
of the Phanerogamia, especially in the Jeaf-cells containing chlo- 
rophylle and in the fleshy bark, at a period long after the nucleus 
has been absorbed. 
It must certainly be admitted as extremely probable that the 
primordial utricle is not only intimately connected with the for- 
mation of the cell-wall structure, but also with the chemico- 
organic processes going on in the cavity of the cell, since it forms 
that organ with which the fluid contents of the cell are in imme- 
diate contact. In this respect the fact that the substance of the 
primordial utricle is entirely distinct from the substance of the 
permanent cell-wall, as shown by its dark colour with iodine 
and its insolubility in acid, is clearly of the highest consequence. 
If the former circumstance might be regarded, as some French 
chemists maintain, as an evidence of the presence of nitrogen in 
an organized body, the primordial utricle would either consist of, 
or be thoroughly imbued with, a nitrogenous substance, and 
during its existence, the cell-wall structure would be entirely 
free from nitrogenous combinations, since this is seldom, and 
then but feebly, coloured yellow by iodine during that period. If 
this really be the case, it explains a fact long known, but re- 
specting the cause of which no clear idea has ever been enter- 
tained. It is well known that young organs abound in nitro- 
genous compounds and the growth of plants, consequently the 
formation of new elementary organs consisting of substance free 
from nitrogen, depends upon the absorption of nitrogenized nu- 
triment. Is not this dependence a proof that the formation of — 
a cell is dependent on the development of a primordial utricle, 
and that nitrogenous nutriment is absolutely necessary to the 
formation of the latter? 
The transient persistence of the primordial utricle shows 
however, that although both the origin and the growth of the © 
cell are dependent upon it, the physiological functions of the — 
cell are not all connected with the primordial utricle. In relation — 
to this however it must not be overlooked that we see the prim- 
