266 PROCESS OF DEVELOPEMENT. CHAP. IV. 



By placing small branches of the Apple, Pear, and 

 Vine with blossoms not expanded in a decoction of 

 logwood, Mr. Knight found that the central vessels 

 were coloured by the decoction. By means of a 

 similar experiment on the same subjects after the 

 fruit was formed, the colouring matter was traced 

 through the mass of the fruit to the base of the 

 stamina.* And hence it appears to me that the 

 flower and fruit do possess the power of elaborating 

 sap for their own developement ; since it seems that 

 the sap ascends to them only in an unelaborated 

 state, as is to be inferred from the ascent of the 

 coloured decoction, which tubes conveying elaborated 

 sap do not seern capable of admitting. 



Inferences Mr. Knight infers, however, from the foregoing 

 Knight, data that the blossom is nourished from the albur- 

 num,-f~ by means, .as I should suppose, of the 

 mingling of the proper juice which the alburnum 

 may be supposed to contain with the sap in its 

 ascent. There may perhaps be something of truth 

 in this remark ; but it is to be observed that most 

 blossoms are accompanied with a calyx, which 

 may be supposed from its similarity to the leaf to 

 perform to the flower or fructification similar 

 functions : and so are the petals themselves similar 

 in structure to the leaves, and may perhaps be capa- 

 ble of performing similar functions. It may be 

 objected, however, to this opinion that when the 

 leaves are by any accident stripped off or destroyed, 



* Phil, Trans. JS05, f Ibid. 1805. 



