1 H 1 3 .] Imperial Ins litute of France. 7 1 



inferior surface, so as to prevent any liquid coming from the 

 lower part of the tree from making its escape into this hole. He 

 made another hole in the tree, and placed a bladder in the same 

 way against the upper surface. He considered the sap collected 

 in the lower bladder as the ascending sap, and that collected in 

 the upper bladder as the descending sap. He gives many obser- 

 vations on the relative proportions of each in different circum- 

 stances. Wishing, in the next place, to determine the route 

 which each of these saps takes in the inside of the tree, he 

 plunged alternately by the two ends branches of trees in coloured 

 infusions. In both cases these infusions appeared to him to 

 follow the woody fibres surrounding the pith. This induces him 

 to ascribe the same route to both saps, in which respect he coin- 

 cides with the result of other experiments made by Mustek 



M. Feburier thinks, likewise, that the ascending sap contri- 

 butes principally to the growth of the branches, the descending 

 to that of the roots. But he thinks that the cambium, or that 

 humour which transudes horizontally from the trunk, and which 

 is looked upon as the matter which "occasions the increase of the 

 tree in thickness, proceeds, like the peculiar juices, from the 

 mixture of the two saps. The presence of the leaves, necessary 

 for the production of the descending sap, is of consequence also 

 for the increase of the plant in thickness. But the buds, which 

 M. du Petit Thouars conceives to act so important a part in that 

 operation, have nothing to do with it, in the opinion of M. 

 Feburier ; for it takes place, says he, as long as the leaves exist, 

 and it ceases as soon as they are removed, whether the buds be 

 left or not. 



As far as concerns the flowers and the fruits, M. Feburier 

 assures us that he has observed the ascending sap, when it pre- 

 dominated, tending to determine the production of simple 

 flowers, and the complete developement of the germs ; that the 

 descending sap, on the contrary, when too abundant, occasions 

 the multiplication of flowers and petals, and the growth of the 

 pericarp, and by consequence of the fleshy part of the fruit ; 

 principles from which it would be easy to deduce many useful 

 practices in gardening, and which explain various practices 

 already pointed out by experience. 



According to M. Feburier, the alburnum deprived of its bark, 

 but kept from the contact of the air, is capable of reproducing, 

 by means of the cambium, the bark and epidermis necessary 

 to cover it, as the bark produces constantly, even when partly 

 separated from the trunk, liber and alburnum. In this point 

 he has for antagonist our colleague M. Paltsot de Beauvois, who 

 has likewise employed himself in the investigation of these 

 difficult qiu-tions, respecting the direction of the sap, and the 

 formation of wood. According to this botanist, this escape of a 



