PHYTOGBNBSIS. 



I return, after tins digression, to my subject. So far I be- 

 lieve I have demonstrated tolerably conclusively, and in accord- 

 ance with nature, that the entire growth of the plan! ' consists 

 only of a formation of cells within cells. Let as now pasfl on 

 to the root. I can contribute but very little to the explana- 

 tion of this part of the subject; for I have not as yet succeeded 

 in arriving at any satisfactory result, from the somewhat limited 

 researches which I have instituted; for instance, 1 have been 

 altogether unsuccessful in deciding the question as to wheth 

 a fluid is secreted at the extremity of the radicle, in which 

 new cells are developed. On the other hand, it is certain that 

 there exists in the extremity of the root a concavo-convex 

 mass (a meniscus) of cellular tissue, in which the process of 

 cell-formation takes place in the same manner as in the pai 

 of the plants which grow in the ascending direction. A chief 

 cause of the elongation of the root consequently consists in 

 this, — that new cells are continually formed in the interior of 

 the existing cells, on the convex side of that mass of cells, 

 while on the concave side, the cells already formed expand 

 simultaneously, and chiefly indeed in the longitudinal direction, 

 and in this way constantly push the extremity of the root 

 before them. 



The third case, the formation of the accidental organs of the 

 plant, I must entirely pass over, as I am altogether unpro- 

 vided with any personal observations upon the subject. Pro- 

 bably, however, the process here is the same as in the previous 

 cases, forMeyen (Physiologie, vol. i, p. 209) observed the cell- 

 nuclei in germinating tubers of Orcludece. Analogy also leads to 

 a similar conclusion, since all these parts are nothing more than 

 morphological modifications of organs which have been already 

 treated of in this memoir. The fourth point, however, still 

 remains for discussion, namely, the increase in thickness 

 plants which form woody stems (Dicotyledons). The origin ami 

 signification of cambium is the nut on which so many young 

 phytologists have already broken their milk-teeth, the Gordiau 

 knot which so many botanical Alexanders have cut instead of 

 untying, and the enigma, for the solution of which almost all 

 the Corypheei of our science have laboured with more or I 



1 I beg to observe, that generalh throughout the entire memoir pfacni 



plants onlv arc referred to. 



