Development, and Structure of the Vegetable CelL 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 Algae was proved by Kiitzing in the same year 

 with the appearance of my essay, probably without his having 

 any knowledge of the latter ; and in 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 lining 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 cellanim seriei interjicitur, est secretionis 

 eella. 



5. In secundaria cella.... nucleus invenitur.... quern Schleiden cellam 



formantem cytoblastura . . . .vocavit, equidem vero parvam cellam 

 tertiariara habeam, ab explicatione impeditam. 



6. In interiore cellae parte citius tardiusve vel una vel plures novse cellae 



plane eodera modo nascuntur. 



7. Organismus potentia ex uno tali cellarum systemate, i. e. reproduc- 



tionis cella,.... aetu e cellarum seriebus aggregatis (quarum unaquaj- 

 que ipsa reproductionis cella esse potest), nunquam ex simplici cella 

 constat, 



18* 



