THE CHEMISTRY OF FRUIT RIPENING. 



BY x\LBERT B. PRESCOTT, F. C. S. 



To forni the seed seems to be the chief end of the plant. When in the vigor 

 of its own maturity, and when receiving the sun's strongest rays and the earth's 

 richest nourishment, the pLant gathers all its resources, and devotes them to the 

 building of the seed. When done, tlie seed itself, the embryo, commonly pos- 

 sesses little substance and serves little use beyond its primary purpose, the re- 

 jn'oduction 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, includ- 

 ing 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 elforts of tlie 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, chemistry has 

 achieved more success than elsewliere in tlie orsfanic world. It is well imder- 

 stood that chemists have no reason to boast of what tliey can do with the pro- 

 ducts of living cells. In an analysis of vegetable or animal products, there is 

 always a percentage, and often a large percentage of unknown matter. It might 

 be named "chemists' 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 un- 

 known bodies, the condition of oriranic analvsis irives 2:ood ground for encour- 

 agenient. Especially in tliis material about the seed, the analyst finds 

 }iumerous compounds of clearly definite chemical character, many of them 

 capable of sure identification and exact separation, even wlien taken in complex 

 mixtures. Working with some of these compounds, an insight into their chemi- 

 cal structure has been obtained ; so that the chemist can bring 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 



