326 On the Buds and Ramifications of Plants. 



that the body of this bud was nourished by the scales which 

 cover it, a& the embryo is by the cotyledons. I shall not 

 here examine whether the embryo be really nourished bv 

 the cotyledons ; but I must deny that the bud is nourished 

 hy the scales, sometimes very arid, which protect it. On 

 the contrary, it is nourished by the juice conveyed to it by 

 the prolongations of the sheath ; for I have had opportuni- 

 ties of remarking that the motion of the sap does not en- 

 tirely cease in the interior of the tree but when the cold is 

 severe, and the buds are then preserved witlxiut having need 

 of nourishment. To insure the conveyance of the sap to 

 the buds, and by these means to shelter them as much as 

 possible from the cold, nature, perhaps, has caused the pro- 

 longations of the sheath to be traversed by one or more 

 zones of wood. 



In regard to the symmetry whidi nature exhibits in the 

 <lisposition of the prolongations of the sheath and the buds, 

 it is as yet inexplicable to us : the hypothesis that the bud 

 pierces the bark at the place where it is thinnest, as for ex- 

 ample in the eves of the leaves, is still very far from the 

 truth. The question is, to know how the prolonged tubular 

 bundles of the medullary sheath which is directed towards 

 the bark^ may meet that thin place without having crept 

 along the interior side of that organ. A thousand other 

 questions might be added, which present ■difficulties equally 

 great. 



It appears to me very probable tbat Hales, Linnaeus, and 

 several other observers who had adopted the hypothesis that 

 the pith is the most active organ in the iiiterior oeconomy 

 of plants, the reproducing organ of the ramifications of 

 the trunk, were not far from discovering the tubular pi'o- 

 lonoations of the sheath, which I discovered by chance. It 

 appears to me also that the green svhstance contained in the 

 medullary sheath has a different origin from that ascribed 

 to it ; and that in regard to the medullary radii, to which 

 Daubenton has given the name of medullary proJongationSy 

 thcv are very different from the organs to which I have given 

 the name of prolongations of the sheath. 



My researches in rca;ard to these organs have made me 

 perceive also some phaenomena respecting the origin of 

 leaves, which were entirely unknown to me. These organs 

 are considered as expansions of the herbaceous tissue of the 

 bark, and of the tubular tissue of the liber. This opinion is 

 among the number of those which cannot be admitted. A 

 leaf, whatever be the place of its insertion, can never be 

 torn off without finding, exactly at the place where it was 



fixed, 



