80 Catalogue of Works 



four hours the ccecum had imbibed seventy-three grains,' and at the 

 end of thirty-six hours, one hundred and seventeen grains of water, and 

 become very turgid. From this time its weight diminished ; and, at the end 

 of thirty-six hours, it had lost fifty-four grains of the water which it had 

 absorbed, and the milk had become putrid. This experiment M. Dutrochet 

 considers as demonstrating that the absorption of the water depends on 

 the fluid in the cavity being denser than that which surrounds the organ ; 

 and that, as long as this dense fluid remains undecomposed, the endosmose, 

 or absorption, continues ; while, as soon as it becomes putrid, the endos- 

 mose ceases, and the water passes out of the organic cavity as rapidly as it 

 had entered it. Farther experiment proved to M. Dutrochet that when the 

 coecum was filled with a thinner fluid than that in which it was immersed, 

 this thin fluid passed out of it into the other. This action he calls exosmose 

 {ex, out, osmos, impulse). He farther proved that fluids of a less density 

 than water, when the solution contained in the coecum is alkaline, produce 

 endosmose ; and, when it is acid, exosmose. 



It may readily be supposed that, if the end of the coecum, instead of 

 being firmly closed, had been furnished with a small tube, the absorbed 

 fluid, or endosmose, instead of producing an excess of turgidity, would 

 have mounted in the tube. This M. Dutrochet found to be the case. He 

 fixed the open end of a glass tube into the ccecum of a chicken filled with 

 a solution of gum and water ; and having immersed the ccecum in rain 

 water, and supported the tube in a vertical position, he found that in 

 twenty-four hours the fluid had ascended to the top of the tube, and that 

 it continued to ascend and overflow at the top for three days. On the 

 third day the water began to sink in the tube ; and on the fourth day, the 

 ccecum being opened, the fluid was found to be putrid. The experiment 

 was repeated with the bladder of the carp, and with the inflated pod of the 

 common bladder senna (Colutea arborescens), with equal success. 



The next thing that M. Dutrochet endeavoured to discover was, the 

 cause of fluids passing through organic substances possessing the action of 

 endosmose and exosmose ; and, as the contact of bodies of different densi- 

 ties, as zinc and copper, is a well known cause of electricity, that power 

 naturally occurred to him as sufficient to account for the phenomena re- 

 lated. He proved this by an experiment, which it would occupy too much 

 room to relate at sufficient length to convey useful ideas to the general 

 reader. The man of leisure and science will have recourse to M. Dutrochet's 

 book ; and the gardener may safely adopt it as a proved fact, that that im- 

 mense power in a bleeding vine, with a bladder tied round the extremity, 

 which Mr. Braddick {Hort. Trans., v. p. 202.) found distended with the 

 rising sap till it became as hard as a cricket ball, and which burst at the 

 end of forty-eight hours, has been clearly traced to the difference between 

 the specific gravity of the water of the soil, and that of the nutritious fluid 

 contained in the almost invisible points, or spongioles, which form the 

 extremities of the fibres of all plants ! 



The effect of temperature on endosmose was, to increase the process, 

 which is a proof of the influence exerted by electricity on the process ; it 

 being a well known fact, that, by increasing the temperature of two metals 

 which produce electricity, the electrical current is increased in intensity. 



In applying his observations to the vital statics of plants, M. Dutrochet's 

 turgidity is shown to be produced and maintained by endosmose, and the 

 accumulated sap re-acted on by the natural elasticity of the sides of the 

 minute organs which contain it. Endosmose in the leaves takes place to 

 supply the vacuum which is created by the transpiration of water from their 

 surfaces. This explains the reason why cut plants absorb water, and why 

 the roots and stem of a plant supply what sap they have to the leaves after 

 being taken out of the ground. The difference of plants, in regard to the 



