the Nitrogenous Matter of Plants. 43 



on this matter, this last fact affords an explanation of the origin 

 of the materials of the cuticle, which, from its composition, can 

 scarcely be derived from the cellulose wall upon which it is 

 placed. However, if this opinion be admissible — and I grant it 

 amounts only to a hypothesis — still there are facts to prove the 

 permeation of the cellulose cell-w^all by the tubular processes 

 derived from the nucleus. Moreover, as these processes do form 

 an anastomotic network in the primordial membrane, it seems 

 fair to suppose that portions of them may penetrate to the 

 under surface of the cuticle, or very nearly to it, and that the 

 detachment of the primordial utricle from the cell-wall is the 

 consequence of the rupture of some of the meshes of this net- 

 work. 



It has just been stated that the canals which usually radiate 

 from the nucleus to the cell-wall break up into still smaller 

 channels in the primordial membrane; this, however, is not 

 always the case, for some of them, and often the most capacious, 

 instead of stopping short at this lamina, penetrate it here and 

 there to anastomose with other similar canals emanating from 

 the nuclei of adjoining cells. This fact may be demonstrated 

 by fixing, with great care, a delicate slice of the epidermis of the 

 flower of Tradescantia virginica on a glass slide, allowing it to 

 become half dried, so as to secure its adhesion, and then brush- 

 ing it with a camel-hair pencil dipped in dilute solution of am- 

 monia, which effects the removal of the cuticle. This done, a 

 viscous network is displayed, which establishes a communication 

 between all the cells of the epidermis, and mainly resembles the 

 regular reticulations of some laticiferous vessels. In making 

 these experiments, it frequently happens that a portion of this 

 network gets removed with the cuticle : this circumstance seems 

 to confirm the notion advanced, that the processes of the nucleus 

 are prolonged as far as the cuticle j for if it were otherwise, it is 

 not readily conceivable why these meshes should be removed 

 with it from the soft-walled layer of subjacent cells. 



The communication of the processes of adjoining cells through 

 their walls has a physiological importance; for it explains how it 

 is that the animal living matter which composes them is distri- 

 buted in the different parts of the same plant, and becomes dis- 

 lodged, as the cells advance in age, in its passage elsewhere, and 

 principally to the periphery, to constitute young cells, where it is 

 known this matter abounds. 



[To be continued.] 



