PHANEROGAMIA : BUD ORGANS. 287 



of parenchyma with very delicate walls, and that the vascular 

 bundles are subsequently prolonged in this : the thickening of the 

 cell- walls begins in those cells lying adjacent to the vascular 

 bundles of those parts on which the bud arises, and gradually pro- 

 ceeds into the bud. 



So far as my observations extend, though they are, I must confess, 

 insufficient, the conversion of the cells of the buds into vascular cells 

 proceeds in all cases from the vascular bundles of the part on which the 

 bud arises. But it is easy to be deceived here, since the parenchyma of 

 the pith of the bud always is in continuity with the parenchyma of the 

 part on which the bud arises, and since the vascular bundles going to 

 the bud more frequently unite with the vascular bundles of the part 

 forming the bud, at the sides than in the upper and under part (where, 

 at least in axillary buds, the lower vascular bundles of the axis are 

 received by the leaf), and therefore it is difficult to perceive the whole 

 of the relations correctly in one section, particularly as it is necessary to 

 go back to the very earliest condition. It is self-evident that the 

 vascular bundles of the terminal bud are but a continuation of the 

 vascular bundles of the axis. On account of the difficulty of this investiga- 

 tion, I by no means set up my observations as affording conclusive argu- 

 ments against views opposed to them. I shall return again to this point 

 when I speak of propagation. 



c. Of the particular Forms of Buds. 



136. A. Buds developing in uninterrupted vegetation. These 

 may also be termed open buds, because they seldom or never exhibit 

 a closed form, since in these the leaves are gradually developed to 

 the perfect form and size, from the perfect rudiments contained in 

 the bud. Yet in these buds the foliatio is always such, that the 

 youngest and tenderest parts are defended from the influence of the 

 atmosphere, and almost wholly enclosed, 



In tropical Monocotyledons, such buds are presented, with few excep- 

 tions, only as terminal buds ; in all other stems they are both terminal 

 and axillary : in this case they approach most nearly to the closed buds 

 of the following divisions. They occur also, though seldom, as adventi- 

 tious buds on the stalks and on the stems of Monocotyledons and Dicoty- 

 ledons, perhaps only in consequence of artificial means used thereto, by 

 cutting or wounding the barks : as an example of this, I may name here 

 the wounded stems of the species of Draccena and Cactus, with neither 

 of which, however, I had opportunity to convince myself fully, whether 

 the developing buds were truly adventitious buds, or rather axillary buds 

 corning into development, which, in Monocotyledons generally, especially 

 on main stems, but also in most Cactece, persist for a very long time in 

 the rudimentary condition. 



B. Buds with vegetation dormant for a certain time. 



1. Buds of Shoots. 



a. Terminal and axillary buds of perennial plants, with periodi- 

 cally dormant vegetation. Of these we are only intimately 



