74 VI1AL ACTIONS. 



the property of elaborating the sap, yet there is this 

 difference between them ; that, while leaves return 

 back into the stem what matters they form, fruit 

 retains the principal part of what it forms for the use 

 of itself or of the seeds it contains. This difference is 

 probably to a considerable extent dependent upon 

 the imperfect condition of the bark of the fruit-stalk, 

 which has little power of carrying off from the fruit 

 the matter which is formed within it. In those cases, 

 however, in which the fruit has stomates, the aqueous 

 particles are given off through the surface of the 

 fruit, which then becomes hard or dry when ripe ; 

 but in others, in which there are no stomates, or very 

 few, or very imperfect ones, the aqueous particles 

 cannot be given off to any considerable amount, and 

 the fruit becomes succulent. 



98. The maturation of the fruit is dependent, then, 

 upon the action of the leaves and roots, and the secre- 

 tions that it forms are principally derived from the 

 former. Consequently, whatever contributes to the 

 healthy condition of the leaves and roots will have a 

 directly beneficial influence upon the fruit, and vice 

 versd. It is, however, certain, that the juices fur- 

 nished by the leaves undergo a further alteration by 

 the vital forces of the fruit itself, which alteration 

 varies according to species. Thus the fruit of the 

 Peach is sweet, but there is no perceptible sweetness 

 in its leaves ; and the fruit of the Fig is sweet and 

 nutritious, while the' leaves of that plant are acrid 

 and deleterious. 



99. Among the immediate causes of the peculiar 



