After these highly interesting discoveries of M. Dutrochet, 

 it is hardly possible to doubt that the force with which the 

 crude sap ascends in the vine and other plants is nothing 

 more than the action of endosmosis, which is carried on by 

 the innumerable cells of the extremities and hairs of the root 

 with their saccharine juices upon the moisture of the soil. 



M. Dutrochet * has in a subsequent memoir announced a 

 change in his views respecting the conducting organs of the 

 sap ; formerly he regarded the spiral vessels as such, at pre- 

 sent the fibrous ligneous cells. The structure of these ele- 

 mentary organs, he observes, is peculiarly adapted to serve for 

 the ascent of the fluids. These fibrous tubes terminate at both 

 ends in extremely fine points ; their cavities are the finest ca- 

 pillary tubes, and the end of the lower tube is articulated with 

 the end of the upper tube. M. Dutrochet states that he is 

 convinced that the ends of these tubes possess free apertures, 

 and in this manner communicate one' with the other. These 

 supposed apertures at the ends of the ligneous tubes have as 

 yet been observed by no German phytotomist, and I am ra- 

 ther inclined to doubt their actual existence ; nay, it even ap- 

 pears that such apertures are quite superfluous ; for it is well 

 known that the crude nutritive sap does not proceed from be- 

 low upwards through the tubes of the ligneous body, but 

 that it can even, and indeed almost as quickly, permeate late- 

 rally, where M. Dutrochet has not yet observed these aper- 

 tures. 



I will cite a passage in opposition to this view from M. 

 Unger's contributions to our knowledge of parasitical plants t, 

 where this illustrious physiologist has also laid down his be- 

 lief respecting the function of the elementary organs of plants, 

 which almost perfectly coincides with my own. The spiral 

 vessel, he says, and the prosenchymatous cell in some degree 

 allied to it, is certainly rather destined originally to conduct 

 the nutritive fluid than to preserve it and prepare it for che- 

 mical changes ; while the parenchymatous cells must rather be 

 regarded as reservoirs of nutrition. The parenchymatous cells 



* Recherches sur les conduits de la seve, et sur les causes de sa progres- 

 sion. Mem. pour servir a 1'histoire anat. et phys. des Veget. et des Anim. 

 i. p. 368. 



f Ann. des Wiener Museums, ii. p. 25. 



