132 FRUIT. 



215. It hag also very little adhesion to its branch ; so that but slight 

 causes are sufficient to detach it from the plant, especially at an early age, 

 when all its parts are tender. 



216. Hence the difficulty of causing Peaches and the like to stone, or to 

 pass over that age, in which the vascular bundles that join them to the 

 branch become woody, and secure them to their place. 



217. For the same reason they are fed almost entirely by other parts, 

 upon secreted matter which they attract to themselves, elaborate, and store 

 up in the cavities of their tissue. 



218. The office of feeding such fruit is performed by young branches 

 which transmit nutriment to it through the bark (69). 



219. But as young branches can only transmit nutriment downward, it 

 follows that, unless a fruit is formed on a part of a branch below a leaf- 

 bud, it must perish, 



220. Unless there is some active vegetation in the stem above the branch 

 on which it grows ; when it may possibly live and feed upon secretions 

 attracted by it from the main stem. 



221. But inferior fruit, consisting at least of the calyx in addition to 

 the pistillum, has a much more powerful communication with the branch ; 

 each division of its calyx having at least one bundle of vascular and 

 fibrous tissue, passing from it into the branch, and acting as a stay upon 

 the centre to prevent its breaking off. 



222. Such fruit may be supposed much more capable of establishing a 

 means of attracting secretions from a distance ; and, consequently, is less 

 liable to perish from want of a supply of food. 



223. It is therefore not so important that an inferior fruit should be fur- 

 nished with growing branches above it. 



224. Fruit is exclusively fed by the secretions prepared for it by other 

 parts ; it is therefore affected by nearly the same circumstances as flowers. 



225. It will be large in proportion to the quantity of food the stem can 

 supply to it ; and small in proportion to the inability of the stem to nourish it. 



226. For this reason, when trees are weak they should be allowed to 

 bear very little, if any, fruit > because a crop of fruit can only tend to in- 

 crease their debility. 



227. And in all cases each fruit should be so far separated from all others 

 as not to be robbed of its food by those in its vicinity. 



228. We find that nature has herself in some measure provided against 

 injury to plants by excessive fecundity, in giving them a power of throw- 

 ing off flowers, the fruit of which cannot be supported. 



229. The flavour of fruit depends upon the existence of certain secre- 

 tions, especially of acid and sugar ; flavour will, consequently, be regulated 

 by the circumstances under which fruit is ripened. 



230. The ripening of fruit is the conversion of acid and other substances 

 into sugar. 



231. As the latter substance cannot be obtained at all in the dark, is less 

 abundant in fruit ripened in diffused light, and most abundant in fruit ex- 

 posed to the direct rays of the sun, the conversion of matter into sugar 

 occurs under the same circumstances as the decomposition of carbonic acid 

 C141 and 279). 



232. Therefore, if fruit be produced in situations much exposed to tho 

 sun, its sweetness will be augmented. 



