40 ANATOMY ANB PHYSIOLOGY OF 



Ohserv. 3. It lias already been remarked that tlie cavities in the pro- 

 toplasm, filled witL. watery cell-sap, sometimes deceptively resemble cells. 

 This is the case in a mnch less degree as long as the protoplasm is only 

 hollowed into distinct isolated cavities, but the similarity becomes very 

 great when the hollows have so increased in number or size, that the layers 

 of protoplasm between them have assiuned the form of thin partitions. 

 In this case the cavities acquire the shape of polyhedral parenchymatous 

 cells ; and those lying on the surface of the mass of protoplasm become 

 rounded off on their free sides, as cells would in such a case ; in shorfc, the 

 resemblance to a delicate-walled cellular tissue could not be greater. Yet 

 if we reflect that the protoplasm is a viscid fluid, which, as its delicate 

 currents shew most distinctly, does not mix with the watery cell-sap, 

 this appearance becomes comprehensible enough ; the protoplasm bears 

 the same relation to the cell-sap as a frothing fluid does to the air con- 

 tained in its bubbles. The unceasing flow and continued transformation 

 of the mass of the protoplasm^ furnish most distinct proof that we have 

 to do with a fluid, and not with an organized structure. We must keep 

 in view this condition of the protoplasm of the young cells, if we would 

 avoid being deceived by the forms which it frequently presents in full- 

 grown cells, especially in those of succulent fruits, e. g., of Grapes. In 

 these it forms not only, in part, a connected frothing mass^ but a portion 

 of it occurs in isolated globular masses, which usually contain in their 

 interior one or more cavities filled with cell-sap, and consequently possess 

 the form of vesicles. These are met with in every gradation of size, from 

 scarcely perceptible vesicles to bodies like cells, some 1-1 00th of an inch 

 in diameter. No more movement in the substance of the protoplasm can 

 be detected in these cases ; on the contrary, the walls of these vesicles 

 exhibit a tolerable degree of flrnmess, so that the comparison of them 

 with cell-like structures is not at all far-fetched. Nevertheless, such a com- 

 parison seems to me out of place ; since none of our means^ — for instance, 

 application of the compressor, or treatment of iodine, — will enable us to 

 discover on these vesicles a membrane which would form a contrast with 

 the contents. Under these circumstances, I can only regard as a mistake 

 Karsten's view {^^ Creation,'' Die Urzeugung. — Bot. Zeitung, 1848, 457 ; 

 ^'Contributions to the Knowledge of Cell-life" — Bot Zeit 1848, 361), 

 according to which these utricles are the rudiments of cells. 



h. Cell-sap, 



In fuU-grov^n cells the protoplasm nstially forms but a very 

 subordinate part, as to mass, of the contents of the cell ; while the 

 watery cell-sap, which at first appeared only in isolated cavities, 

 formed by degrees in the protoplasm, fills the whole cavity of the 

 cell The quantity of it is subject to variation, according as the 

 plant has absorbed or evaporated more water ; the decrease, how- 

 ever, cannot descend below a certain limit in the cells of most 

 organs of the higlier plants, without destroying the life of the 

 vejui* 



Although the cell-sap always contains in solution a series of 

 organic and inorganic compounds, as a general rule it appears to 

 the eyB like pure water, since it is but rarely that colouring mat- 



