104 M. Dutrochefs Discoveries in Vegetable Physiology. 



through which the sap ascends. The cellular cortical part of 

 the spongioles is transparent, and covered with minute cor- 

 puscles. 



These organs possess the faculty of introducing forcibly into 

 their cavity, and through their sides, the water which is in con- 

 tact with their exterior surface ; and they do this in such a man- 

 ner as to expel from their cavity substances which it formerly 

 contained. To this peculiar action, which will probably be 

 found to be an electrical one, M. Dutrochet gives the name of 

 Endosmose, or impulse inward, from the Greek words svdov, in- 

 ward, and cbapog, an impulse. This action, however, does not 

 take place unless the fluid within the spongioles is specifically 

 heavier than the water or fluid without. When the fluid with- 

 in the cavity is specifically lighter than the fluid without, the 

 inner fluid passes out^with the same rapidity with which it 

 would have entered in the other case. This action M. Dutro- 

 chet calls Exosmose, or impulse outwards, from the Greek 

 words gg, out, and m/aoc, an impulse. 



The following experiment is illustrative of these two actions : 

 M. Dutrochet took the ccecum or blind gut of a young chicken, 

 into which, when well cleaned, he put 196 grains of milk, which 

 occupied one half of its cavity. Its mouth being firmly tied, 

 it was placed in water. After 24 hours the ccecum had im- 

 bibed 73 grains of water; and at the end of 36 hours, 117 

 grains, which rendered it very turgid. The weight of the cce- 

 cum now diminished ; and after 36 hours it had lost 54 grains 

 of the imbibed water. The milky fluid had become putrid, 

 and had become specifically lighter than the water without. 



The turgidity which is the necessary consequence of eiidos- 

 mose causes the ascent of the sap. The cavity of the spon- 

 gioles being extended by the imbibed .water, the sides of the 

 cavity react on the contained fluid, and force it upwards. This 

 M: Dutrochet proved in the following manner : — 



He took a glass tube 24 inches long, and about one-fifth of 

 an English inch in diameter, and he fixed the open end in the 

 ccecum of a chicken, filled with a solution of gum arabic. The 

 ccecum being placed in rain water, and the glass tube held ver- 

 tically, the fluid during 24 hours rose in the tube and reached 

 the top, over which it flowed, which it continued to do till the 



