Vegetable Physiology for the Year \?>^Q, G^ 



In every monocotyledonous plant there may be detached 

 from the basis of each leaf a greater or smaller number of 

 vascular bundles, which run, in their manifold, slanting and 

 extended course, near to any point of the axis, and from thence, 

 separating from one another towards the horizontal side, 

 continue to descend right and left with various contortions, 

 continually returning in a slanting direction towards the peri- 

 phery. They end by taking a perpendicular course, which 

 allows of their condensing themselves into a peripherical zone 

 of various firmness and thickness, in which, however, the 

 same r)rder of superposition is always retained ; in return for 

 which the most recent bundles are always placed upon the 

 others. 



2. What invariable laws govern this general arrange- 

 ment? 



Since each leaf, at its origin from the stalk, comes forth with 

 a circular basis in the middle of the bud, and is carried in its 

 growth like a spiral line to a higher and peripherical spot, as 

 it continues to surround the whole circumference of the stalk; 

 and since, in consequence, it can only embrace a gradually 

 smaller arc, it necessarily must follow that the lower course of 

 each vascular bundle represents the place which it occupied 

 during the time when the leaf was still inclosed in the bud ; 

 and the upper organized course, during the progression of the 

 leaf itself, gradually depends on the conditions, as modifica- 

 tions of an invariable law, which are observed in this process. 



3. To what particular modifications can the general and 

 constant type of this organization be subjected? 



The bud, which gives origin to new individuals, ceases to 

 develop itself as soon as it has arrived at a certain limit, or 

 continues in an indefinite manner its progressive development. 

 The limit of the first is fixed by the terminal position of the 

 inflorescence, which in the second is an axillary one. The 

 florescent part of the stalk is held fixed by the upper courses 

 of the vascular fibres, and enjoys therefore the conditions in- 

 herent in them, which are -those of endogenitiveness. The 

 centripetal or centrifugal characters of the inflorescence itself 

 cause in the structure of the inflorescent part only a slight mo- 

 dification, which is still less evident in the lower parts of the 

 stalk, and is connected with the period of the development of 

 the axillary bud, whence originate the inflorescent branches. 

 The separation and displacement of the leaves is effected as it 

 were in a single or in two spiral lines, which run round at the 

 same time in opposite directions. The greater or less per- 

 pendicular distance, and the greater or less lateral divergence 

 of the leavesj (setting aside the relation of the basis to the 



Phil. MafT, S. 3. Vol. 12. A^o. 71. Ja?i. 1838. K 



