OP THE SEED. 767 



part in the changes which are taking place during the ripening 

 of the fruit. M. Fremy has recently discovered a new acid in 

 fruits, to which he has given the name of celluHc acid; but at 

 present nothing is known of its action or use in the plant. 



The time in which a fruit is considered ripe varies in different 

 cases. When the pericarp is of a dry nature, the fruit is looked 

 upon as ripe just before it opens ; but when the pericarp is of a 

 pulpy nature and edible, we commonly regard it as mature 

 when most agreeable as food. Hence the Apple is considered 

 to be ripe in a state in which the Medlar would be regarded as 

 unripe and unfit for food. 



When succulent fruits are ripe, they undergo another change, 

 a species of oxidation, which produces either a decay, or 

 bletting of their tissues, as it has been called by Lindley. This 

 bletting, according to Berard, is especiaDy evident in the fruits 

 of the Pomacese and Ebenacea, and it would appear that the 

 more austere the fruit is, the more it is capable of bletting regu- 

 larly. This bletting appears to be peculiar to such fruits, and 

 may .be regarded as a state intermediate between maturity and 

 decay. A Jargonelle Pear in passing from ripeness to bletting, 

 according to Berard, loses a great deal of water (83-88, which 

 it contains when ripe, being reduced to 62-73); pretty much 

 sugar (11-52, being reduced to 8*77); and a httle hgnine (2'19, 

 reduced to 1-85) ; but it acquires, at the same time, rather more 

 malic acid, gum, and animal matter. 



The time required by different plants for ripening their fruits 

 varies much, but almost all fruits come to maturity in a few 

 months. Some, as those of Grasses generally, in a few days 

 commonly; while others, as some of the Coniferae, &c., require 

 more than twelve months. 



4. Of the Seed. — The structure and general characters of 

 the seed, as well as the origin and progressive development of 

 its parts, have been already fully alluded to in the section of 

 this work which is especially devoted to the Seed (p. 335 — 351). 



Our limited space prevents us from alluding to the multitude . 

 of ways and contrivances by which the natural dissemination of 

 seeds is effected ; and to the number of seeds produced by plants. 

 Sufl&ce it to say, that in all cases, a great many more seeds are 

 matured than are required for the propagation of the species ; 

 and thus, on the one hand, whUe the extinction of the species in 

 consequence of the decay of seeds, and their use for food, &c., 

 by animals, is provided against, at the same time, their too great 

 increase is prevented. 



Vitality of Seeds. — Seeds vary very much as to the time which 

 they retain their vitality. By retaining vitahty we mean pre- 

 serving their power of germinating. This vitality is frequently 

 lost long before they lose their value for food. Some seeds as 

 those of an oily or mucilaginous nature, or which contain much 

 3 D 



