66 ANATOMY AND PHYSIOLOGY OF 



Since tlie discovery of endosmose, most vegetable physiologists 

 have assumed it as an axiom that the absorption by cells depends 

 wholly and solely upon the laws of endosmose, none of the pecu- 

 liar forces of the living cell co-operating. All the conditions 

 to bring about strong endosmose do really exist in the living 

 vegetable cell, namely, a membrane freely penetiable by watery 

 fluids ; on the one side of this the cell-sap which contains proteine 

 substances, dextrine, sugar, fee, in solution, on the other side the 

 water oecurrmg in nature, in the state of an extremely diluted 

 saline solution. This renders it readily explicable how cells which 

 are laid in water swell up rapidly, in many cases, if they contain 

 a concentrated protoplasm and have not firm walls (e. g,, many 

 pollen-grains), the powerful absorption of water causing them to 

 burst; and how, on the other hand, if they are laid in a strong 

 solution of sugar, gum, &c., they become emptied and collapse. 

 Under these circumstances, the assumption that the absorption of 

 the cells will be regulated by the laws of endosmose, is fully justi- 

 fied, yet special proofs of this can only be partially advanced, be- 

 cause on one side the phenomena of absorption are too little known 

 in many respects, and on the other side the theory of endosmose 

 is not yet perfect enough to allow of our making ou.t in all cases 

 the share it has in any given phenomenon. 



According to the researches of Th. de Saussure ('' Eecherch. 

 chion. $ur la Vegetf 274), healthy and diseased roots behave very 

 differently in reference to absorption, the latter taking up the 

 substances dissolved in the water in far greater quantity than the 

 healthy roots ; the action of a poisonous substance (sulphate of 

 copper) had the same result as disease of the roots, for it was not 

 only taken up in relatively very much greater quantity, but also 

 caused the absorption of other substances v hich were placed with 

 it for absorption by the roots, in larger proportion than occurred 

 in healthy roots. This condition alone would excite great doubti 

 of the opinion of many physiologists, e. g., of Treviranus, that the 

 absorption is an expression of vital force, since it involves the 

 contradiction that weakening and destruction of life are combined 

 with au exaltation of an activity dependant on it ; while it would 

 not be at all striking for changes to occur in a diseased or dead 

 cell, which would cause an alteration in the physical character of the 

 cell and of the phenomena standing in connexion with it. If the 

 roots are healthy, they take up different substances in very dif- 

 ferent quantity from solutions of like degree of concentration 

 (Saussu.re experimented with solutions containing twelve grains 

 of foreign matter in forty cubic inches of water), and they separate 

 the fluid into a dilute solution which they absorb, and a more 

 ooncentrated which they leave behind. 



Ohseo-^, The distinctions which occur in solutions of different sub- 

 stances, are very considera,ble. gaus&ure in each caso allowed half the 



