The Sex and Generative Organs of Plants, 263 



in that of breadth. The first shews itself in the stem and its 

 parts, the branches and twigs, the second in the leaves. 

 Both these parts are necessary to each other. The stem is 

 the support, it endures, and is lasting ; the leaf is that which is 

 born, evanescent, and decaying. The stem displays in its 

 interior formation, i, e. its construction from cells and vessels, 

 a great degree of symmetry. The leaves are, as regards their 

 construction from such elementary organs, unsymmetrical. 

 For instance, if one compares a complete section or a regular 

 part of a section of a stem with another one of equal size, 

 cells and vessels will be discovered everywhere in the 

 corresponding portions in like number, size and form, and 

 relative position. 



It is different with leaves, since their elementary organs 

 are not exactly in the same proportion on one side, and on the 

 other, when counted by the median plane marked by the 

 midrib, and thus, a section from above downwards shews 

 differences in the number, form, and arrangement of the 

 elementary organs. 



The stem placed on the root on which it is supported, is 

 by means of the juices, which are conducted through it, the 

 former and nourisher of the leaves ; they, on the contrary, 

 being provided with special respiratory organs, help to in- 

 crease, prepare, alter and ennoble the sap. From the mu- 

 tual action of these parts on each other, the nourishment 

 and health of the whole results. The juices which carry 

 the matter capable of being organised, are in the progress 

 of growth worked into soHd parts, and the stem, as being the 

 enduring and stronger portion of the vegetable, from year to 

 year increases in mass, while the leaves, after they have for 

 a certain time aided in this process, fall off, and are replaced 

 by new ones. The whole of this system of growth, of- 

 ten containing innumerable members, is ruled by the im- 

 pulse of self-preservation, so long as flowering does not take 

 place. With the approach of flowering, another higher life 



2 L 



