140 ENDOGENS. [BOOK ir. 



many herbs, in which growth by addition to the outside is 

 wholly departed from, the reverse taking place ; that is to say, 

 their diameter increasing by addition to the inside. As the 

 seeds of such plants are formed with only one cotyledon, they 

 are called monocotyledonous ; and their growth being from 

 the inside, they are also named endogens. In these plants 

 the functions of the leaves, flowers, and fruit are in nowise 

 different from those of the apple ; their peculiarity consisting 

 only in the mode of forming their stems. When a monocoty- 

 ledonous seed has vegetated, it usually does not disentangle 

 its cotyledon from the testa, but simply protrudes the collum 

 and the radicle ; the cotyledon swelling, and remaining firmly 

 encased in the seminal integuments. The radicle shoots 

 downwards to become root ; and a leaf is emitted from the 

 side of the collum. This first leaf is succeeded by another 

 half-facing it, and arising from its axil ; the second produces 

 a third half-facing it, and arising also from its axil ; and, in 

 this manner, the spiral production of leaves continues, until 

 the plant, if caulescent, is ready to produce its stem. Up to 

 this period, no stem having been formed, it has necessarily 

 happened that the bases of the leaves hitherto produced have 

 been all upon nearly the same plane : and, as each has been 

 produced from the bosom of the other without any such inter- 

 vening space as occurs in dicotyledonous plants, it would be 

 impossible for the matter of wood, if any were formed, to be 

 sent downwards around the circumference of the plant ; it 

 would, on the contrary, have been necessarily deposited in 

 the centre. In point of fact, however, no deposit of wood 

 like that of dicotyledons takes place, either now or hereafter. 

 The union of the bases of the leaves has formed a fleshy stock, 

 cormus, or plate, which, if examined, will be found to consist 

 of a mass of cellular tissue, traversed by perpendicular and 

 horizontal bundles of vascular and woody tissue, connected 

 with the veins of the leaves, of which they are manifest pro- 

 longations downwards; and there is no trace of separable 

 bark, medullary rays, or central pith : the whole body being 

 a mass of pith, woody, and vascular tissue, mixed together. 



To understand this formation yet more clearly, consider 

 for a moment the internal structure of the petiole of a dicoty- 



