!^^^5^^ Braun on the Vegetable Individual. ^jf^} 



merely its cast-ofF garment, its perishing shell. Cell-formation 

 by division (ealled the " merismatic " or '^ wandstiindige ") is 

 that which obtains through the whole realm of vegetative deve- 

 lopment; while free cell-formation occurs only in fructification. 

 Thus, the same phaenomenon, which, regarded as endogenous 

 cell-formation, seemed so favourable to the importance of the 

 cell as the vegetable individual, when more justly comprehended 

 only brings us back to the divisibility of the vegetable organism, 

 repeated in the most heterogeneous spheres. But still more : 

 even the cell whose contents are not converted by division into 

 new cells, but remain simple, presents phsenomena which can 

 hardly be reconciled with their view by those who regard such a 

 cell as an individual, isolated in space and independent in time. 

 In the genera Vaucheria, Bnjopsis, Caulerpa, and other related 

 Algse in the family of Siphonice, we find such cases, examples of 

 the most extraordinary kind of cell-formation. The single cell, 

 which forms the vegetable organism of these plants, has in fact 

 a development which may continue indefinitely. Certain parts 

 of the elongated stem-like cell shoot forth into branches which 

 lengthen by an independent terminal growth, without separating 

 from the cavity of the maternal trunk by any partition. The 

 principal trunk of the cell is either creeping, with an indefinite 

 terminal growth, though dying off from behind {Caulerpa pro- 

 lifera *), or it is upright and deciduous, while the sucker-like 

 branches, club-shaped at the ends, and filled with a denser con- 

 tents, are perennial {Vaucheria tuberosaf). In both cases the 

 branches separate from the dying trunk, closing up at the 

 bottom ; and thousands of new trunks may thus be produced 

 without any proper cell-formation. Thus the cell leads us back 

 to the point from which we started at the tree ; and, as we could 

 not refuse individuality to the ramifications of the tree, neither 

 can we refuse it to the ramifications of the cell. Hence we can- 

 not regard the cell as an absolutely single being, completely iso- 

 lated and indivisible. Shall we penetrate still further into the 

 anatomy of the cell itself, in the hope of possibly finding a valid 

 vegetable individual ? All that we discover here is, first, the 

 vesicles, spherules and granules in the contents of the cell (amy- 

 lum, chlorophyll and other pigment-vesicles, spherules of fat, 

 and, finally, the granules of the viscous cell-contents, whose 

 chemical nature it is difficult to determine) ; and secondly, the 



* Cf. Nageli's important paper on this plant (Zeitschrift fiir wissen. Bot. 

 i. p. 134), especially the exposition of the above-mentioned relations he- 

 ginning p. 158. 



t A new species from the vicinity of Luke Neuenberg in Switzerland, 

 remarkable for its purely furcated ramifications, with constrictions at the 

 bottom of the branches, as well as for the club-shaped suckers at the ends. 



