THE YEC4ETABLE CELL. 



67 



Sugar . . . 



Humous Extractive 



14-7 

 13 



4 

 14-4 

 12 



8 

 47 



9 

 29 



5 



parts 



solution to be abaorbccl, therefore fifty parts of the dihsolved biibj>tance 

 should have been abBorbed, instead of which Polygonum Fersicaria 

 absorbed of, — 



Chloride of Potasbum . . 

 „ Sodium , * . 



Nitrate of Lime .... 

 Sulphate of Lime . . . 

 Chloride of Ammonium 

 Acetate of Lime . . 

 Sulphate of Copper , . . 

 Gum ... ... 



Sa^ussure tried to explain these differences in the absorption from phy- 

 sical differences in the solutions, especially by the assumption that the 

 quantity of substance absorbed, depended on the greater or less degree of 

 viscidity which it imparted to the water by its solution. He regarded, 

 namely, the cell-membrane as a very fine filter, through which not only 

 would a denser solution penetrate more slowly, but which was also ca- 

 pable of separating the solution into a more concentrated and a more 

 diluted one. This explanation is certainly not sufficient, since we have 

 no proof that the finest filter can effect such a separation of a fluid ; and 

 secondly, Triiichiiietti found that the quantity of substances taken up by 

 i^oots did not run parallel with the viscidity of their solutions. But there 

 is nothing in the result of these experiments which would be in opposi- 

 tion to the laws of endosmose, in particular the separation into a thinner 

 and a denser fluid btand in agreement with these, since many observations 

 (of Jenchau, Brucke) have shewn, that in endosmose the fluid does not 

 necessarily penetrate the septum in toto, but that in many cases a dilute 

 fluid or merely water goes through. "We are certainly not in a condition 

 to state at present how one salt passes over in this, another in that, quan- 

 tity ; to do this it would be necessary to know the contents of the vege- 

 table cells and the relation in which they stand to the cell-membrane and 

 to the different solutions ; but no contradiction exists between the phe- 

 nomena referred to and endosmose. Formerly it might have been con- 

 cluded from the different behaviour of diseased and healthy roots, that 

 absorption was not a true physical process, but that the force of the living 

 plant was to be considered in reference to it ; but not to speak of the 

 above-noticed contradiction that a vital act would be exalted in a dead 

 cell, there occur in the disease and death of a cell, two alterations which 

 cannot be without influence on the endosmose. In the first place the 

 living cell exhibits a certain tension, which is lost in the dead cell; in the 

 second place the primordial utricle is very readily detached from the 

 inside of the cell-wall m diseased or dead cells ; these two circumstances 

 place the cell-wall in a condition essentially different from the normal 

 one, and we may readily conceive that the endosmotic force of the cell- 

 wall becomes essentially different, and that the dead cell-membrane is 

 penetrated much more easily and quickly than the wall of the living cell. 

 There are frequent opportunities of observing the more easy penetration 

 of a diseased or dead cell, in microscopic investigations where tincture of 

 iodine is applied ; for, in the Oonfervce. for example, where several cells 



r 2 



