Development, and Structure of the VegetableCell. 267 
By this work I hoped not only to convince histologists of the 
compound structure of the elementary organs of vegetable tissue, 
the youngest member of which is the nuclear corpuscle, but also 
to prove to physiologists the intimate affinity of all the different 
endogenous members of one and the same system of cells, as 
well as the mutual action which takes place between the con- 
stituent walls of the endogenous cells and their fluid and solid 
contents—a mutual action from which not only the most material 
changes of form of the original structureless cell-wall proceed, 
but also the multiform and peculiar chemical combinations of its 
organic material, 
The existence of a secondary cell in the tissue-cells of the 
large class of Algze was proved by Kiitzing in the same year 
with the appearance of my essay, probably without his having 
any knowledge of the latter; and im the following year Mohl 
announced this structure, as ascertained by me, to be common 
to all plant-cells. 
One portion of my work therefore promised to be serviceable 
immediately after its appearance,—the composite structure of 
the elementary organs of plants being recognized by the most 
experienced of histologists. But with respect to the functions 
of the different elements of this microcosm, and their purpose, I 
had not the good fortune to obtain Mohl’s acquiescence ; for 
whilst I sought to establish a successive endogenous formation 
of cells within one another, and was convinced of the continua- 
tion of an assimilative process in their often thickened and 
stratified walls, that illustrious observer adopted an opposite 
theory, and assumed that the thin, still nitrogenous delicate 
membrane which, at a certain stage in the development of most 
tissue-cells of plants, forms a linmg to an outer and ligneous 
cell—the same membrane which I regarded as an endogenous 
secondary cell, growing eventually ligneous itself—is the first in 
origin (in Schleiden’s sense) around the nucleus, the primary 
membrane of the whole system of layers found in the fully de- 
veloped tissue-cell. He moreover implied that this cell-mem- 
brane, which he called the “ primordial layer,’ remains un- 
_ brum, quod interdum huic cellarum seriei interjicitur, est secretionis 
cella. 
5. In secundaria cella....nucleus invenitur....quem Schleiden cellam 
formantem cytoblastum....vocavit, equidem vero parvam cellam 
tertiariam habeam, ab explicatione impeditam. 
6. In interiore celle parte citius tardiusve vel una vel plures nove celle 
plane eodem modo nascuntur. 
7. Organismus potentia ex uno tali cellarum systemate, i.e. reproduc- 
tionis cella,....actu e cellarum seriebus aggregatis (quarum unaque- 
que ipsa reproductionis cella esse potest), nunquam ex simplici cella 
constat, 
18% 
