THE CHEMISTRY OF FRUIT-RIPENING. 461 



all its resources, and devotes them to the building of the seed. When 

 done, the seed itself, the embryo, commonly possesses little substance 

 and serves little use beyond its primary purpose, the reproduction of 

 the plant. But in the coatings and coverings of the seed we find a 

 large and abundant supply of substances, in variety and quantity the 

 rarest and richest stock in the vegetable commonwealth. Indeed, the 

 wrappings of seed-germs constitute the especial provision for the 

 nourishment of the human race. The seeds enveloped with starch 

 and albuminoids, as in the cereal grains, make up "the staff of life" 

 for man. Seeds with oily coatings, including the nuts, present a good 

 supply of fats for food. The seeds with succulent coverings, the 

 fruits, yield a great number of sharply-defined substances, most of 

 which claim the approval of man, and some of which require for their 

 due application the best efforts of the human intellect. Without the 

 grains, the fruits, and the nuts, man would be left to browse with the 

 ox and prey with the wolf. 



In this abundant material gathered around the seed-germs, chem- 

 istry has achieved more success than elsewhere in the organic world. 

 It is well understood that chemists have no reason to boast of what 

 they can do with the products of living cells. In an analysis of vege- 

 table or animal products, there is always a percentage, and often a 

 large percentage, of unknown matter: It might be named " chemist's 

 dirt ;" not " matter out of place," but simply " matter unknown." It 

 has weight, it may have color and consistence, but it responds to no 

 inquiries and yields to no suggestions. Like an open polar sea, it 

 baffles and invites and baffles again. But, with all due reservation 

 for unknown bodies, the condition of organic analysis gives good 

 ground for encouragement. Especially in this material about the 

 seed, the analyst finds numerous compounds of clearly definite chemi- 

 cal character, many of them capable of sure identification and exact 

 separation, even when taken in complex mixtures. Working with 

 some of these compounds, an insight into their chemical structure has 

 been obtained ; so that the chemist can brins; together the materials 

 and conditions for their production. In the products of the peach, at 

 every autumn's ripening, certain chemical changes occur in the kernel 

 under your hand changes as well known to science and capable of as 

 exact quantitative statement as the local changes of the planets in the 

 solar system. Forty-four years ago, Liebig and his fellow-workers 

 discovered certain links in those chemical changes, in the products 

 of the almond family, and the discovery was an era in chemical 

 science. 



The chemistry of the covered seed is of interest not only for the 

 quality of the compounds found in it, but, quite as much, for the his- 

 tory of these compounds, the chemical changes of seed and fruit-ripen- 

 ing in the plant. These changes differ in their general character from 

 other changes of plant chemistry, coinciding more nearly with the 



