SECT. IV. DECOMPOSITE ORGANS. 267 



the fruit does not come to maturity ; but still the 

 calyx or corolla may perform some peculiar and in- 

 dispensable function to such flowers as are furnished 

 with them : and there are also plants in which the 

 flower is completely developed before ever the leaves 

 expand ; as in the case of Daphne Mezereon and 

 the Apricot, which seems to imply that they are 

 capable of elaborating the sap necessary to their own 

 developement. 



But the office of the tubes of the bark does not 

 seem to have been ascertained in the fruit-stalk, 

 though Mr. Knight thinks it cannot be the same with 

 that of the tubes of the leaf-stalk namely, the con- 

 ducting of the returning proper juice for the purpose 

 of forming new parts below ; and this he thinks he 

 has proved by the following experiment : When 

 the end of a shoot of the Vine immediately above a 

 bunch of grapes was pinched off as soon as it had 

 made its appearance, and the leaf opposite allowed 

 to remain, the wood below increased as usual ; but 

 when the leaf opposite was taken off also, then the 

 wood below ceased to elongate, and remained in 

 form and substance similar to the fruit-stalk. Hence 

 Mr. Knight concludes that the tubes of the bark do 

 not in the fruit-stalk conduct a fluid downwards that 

 is capable of forming wood ; and yet, as it is likely 

 that the motion of the tubes of the bark is in all 

 cases retrograde, he supposes that the function of the 

 tubes of the bark of the fruit-stalk may be that of 

 carrying oft' from the fruit any superfluous humours 



