APPENDIX. 57 



firm the assumption of Meneghini, that in Draccena Draco 

 the perfectly amplexicaul leaf is changed into one which 

 does not surround the stem, but an essential distinction 

 exists, in that Meneghini states this change to begin after 

 the completion of the leaf, and to be continued further in 

 the cicatrix after the fall of the leaf; while the result of 

 my investigation is, that the leaf only surrounds the stem 

 so long as the part of the axis of the bud on which it is 

 inserted is still in a rudimentary condition, and the thick- 

 ness has not, or scarcely, exceeded a millimeter; that in the 

 next older leaflet the borders are already \ of the cir- 

 cumference of the stem apart, and the permanent propor- 

 tion between the base of the leaf and the circumference 

 of the stem already exists in the leaflets situated but a 

 couple of internodes further out. This difference in the 

 results of our investigations is very much the more im- 

 portant, as will be shown further on, in so far that such an 

 alteration of the proportion of the breadth of the base of 

 the leaf and the circumference of the developed stem 

 must cause extraordinarily great changes, which we never 

 see, in the internal structure of the stem, and in its 

 growth in thickness ; while such changes, if they begin in 

 a portion of the stem a millimeter thick, and cease in a 

 part only a few millimeters in diameter, take place in a 

 part which consists merely of soft cellular tissue in full 

 process of multiplication, which exhibits extremely rapid 

 growth in all its parts, in which, therefore, the softness 

 and continual metamorphosis of its substance, present no 

 mechanical hinderance to a more rapid development of 

 one part, and a less extensive development of another. 

 That these changes of form exert influence on the lateral 

 divergence of the vascular bundles cannot, indeed, be 

 denied ; but, on the other hand I cannot think, that they 

 are the sole, or even the principal cause of their oblique 

 course, inasmuch as this occurs in the vascular bundles 

 of Aletris fragrans, although no trace of an alteration of 

 proportion between the base of the leaf and the circum- 

 ference of the stem is to be discovered here. 



