362 Proceedings of the 



of moticeci, polygamies; and diced, not only in their flowers, but 

 their leaves, stems, branches, roots, &c. It would be useless to detail 

 their minute differences of organization, as they can only be under- 

 stood by a close inspection of the natural flower. M. Giroux ima- 

 gined that there are special relations between the male flowers and 

 the peripheric beds of the stem, and between the female flowers and 

 the central beds ; and with a view of ascertaining the reality and 

 generality of the fact, he extended his observations to an immense 

 number of plants, both endogenous and exogenous. From these ob- 

 servations he concludes, that when the vegetation of the superficial 

 beds exhausts itself in forming leaves, the plant becomes adapted for 

 the production of female flowers ; and that when the central beds 

 exhaust themselves in producing female flowers, the plant becomes 

 adapted for the production of male flowers, and, therefore, that the 

 distribution of the sexes in the monceci and polygamies depends on the 

 relative state of these two orders of vegetation. The reporters con- 

 sider this last theory as, at least, premature, but, on the whole, 

 recommend the memoir to the approbation of the Academy. 



Exogenous Plants. On the 19th of September, a report was made 

 by M. Auguste de St. Hilaire, in the name of himself and Messrs. 

 Desfontaines and Mirbel, on M. Giroux de Busaringues' memoir on the 

 evolution and growth of exogenous plants. The report commences 

 by giving the following seventeen propositions, as the result of the 

 arguments and experiments detailed in the memoir. 1. Plants are 

 divided into beds (couches), more or less exterior, and more or less 

 interior. 2. There are two causes of vegetation: the gas contained 

 in the atmosphere, and the humidity existing in the soil. 3. The 

 exterior beds, or layers (couches') of plants are, during their evolu- 

 tion, principally subjected to the influence of the atmosphere; the 

 interior beds to that of the humidity of the soil. The development 

 of both is in proportion to the relative predominance of these two 

 influences. 4. At the point of junction of each of the leaves of 

 the plant at its birth, these two causes of vegetation combine, and 

 by that combination, produce an interior longitudinal fold, which 

 embraces all the layers of the stem from the pith to the circum- 

 ference, and it is from this fold that the buds derive their origin. 

 5. Each foliaceous organ of the bud is specially derived from aae 

 of the folds of the superficial beds of the stem. 6. The leaf 

 itself produces the bark and a part of the interior bed. These 

 interior parts form the nerves, which are duplicatures or folds 

 united under a cortical envelope. 7. /The size of a nerve is always 

 in proportion to the number and volume of those which border on 

 it ; the size of the petioles to the number and volume of the princi- 

 pal nerves ; the size of the stem to the number and volume of the 

 petioles which it bears ; the size of a principal stem to the number and 

 volume of its vessels. 8. When no obstacle exists, every longitu- 

 dinal fold formed in the stem continues to the root, and every 



