246 Dr. A. Braun on the Vegetable Individual. 



fibres, which compose the cell-membrane according to the old 

 view advanced by Grew and lately revived by Meyen* and 

 J. Agardh f. These parts, it is true, have often been regarded 

 as the elementary forms % of plants, or their primary " indivi- 

 dualized ^' bodies § ; the attempts, however, to represent them as 

 the true and real vegetable individuals are not numerous ; and 

 they astonish us by their daring rather than entice to imitation. 

 Turpin, who commenced by considering plants to be composed^ 

 of different kinds of individual cells, which he compared with 

 various lower plants (especially the Algae-genera Protococcus and 

 Conferva), afterwards expanded his views, so as to regard the 

 cells themselves as individuals of a second rank ; while he consi- 

 dered the true primary individuals to be the granules of the cell- 

 contents, from which, in his opinion, the cell (cell-wall) is formed 

 by agglomeration ||. Mayer of Bonn, basing his theory upon 

 molecular motions, considers the smallest granules of the cell- 

 contents as individuals possessing animal life (biospheres), which 

 build up plants for their dwellings. " Like hamadryads these 

 sensitive monads inhabit the secret halls of the bark-palaces we 



two biBiJ oldens o:t ban 



* Meyen, Pflanzenphysiol. i. p. 45 ; answered hy Molil, iii his Ver- 

 mischte Schriften, p. 314. 



t J. Agardh, De Cell. Veg. fibrillis tenuissimis contexta (1852). Not- 

 withstanding the importance of the author's new investigations, they still 

 need a more searching examination, as some points directly contradict 

 well-ascertained facts, e. g. the direct transition of the fibres from the 

 outer to the inner layers of the cell-wall. The whole theory of the forma- 

 tion of cells by the uninterrupted growth of fibres cannot be admitted in ; 

 view of the undoubted independence of the formation of the cell- wall from; i 

 the contents. Mohl is certainly right in regarding the fibrous division.,, 

 and divisibility of many cellular tissues as a mere structural relation of the 

 membrane (which in other parts is continuous) ; and he thinks it depends ' ' 

 upon the peculiar mode of agglomeration of the molecules. As such mole-'' 

 cules of the cell- wall are invisible, I think it preferable to regard it as de- < 

 pendent upon a regular change of the relations of density. r 



X Kiitzing, Phil. Bot. i. p. 125, 129, does not regard the cell as the 

 elementary form of plants, but as a complicated structure itself, and pre- 

 ceded by many other more simple forms, which he comprehends under the 

 name of " molecular tissue," and which, he says, present in themselves 

 many lower vegetable forms ; — plants which are not even cells ! 



§ Unger, Grundz. d. Anat. u. Phys. der Pflanzen, p. 4. The cell is re- 

 presented as the " elementary vegetable organ ;" but the vesicles, fibres 

 and granules within it are further distinguished as very minute, "indivi- 

 dualized " bodies. 



II Turpin, " Sur le nombre deux" (Mem. du Musee, xvi. 1827, p. 305) : 

 " Ainsi des individus globuleux, rapproches simplement contigus, forment 

 la membrane de la vesicule Individu du tissu cellulaire, le filament Individu 

 du tissu tigellulaire, et la membrane cuticulaire Individu. Des agglome- 

 rations de ces derniers constituent les Individualites, provenantes des 

 bourgeons developpes, et enfin, celles-ci achhweni P IndivlduaUte comj^osee 

 d'un arbre." I>m** ftnoU arfj &H^ oroor 



