Page:Popular Science Monthly Volume 12.djvu/478

462 changes of animal chemistry. Taking for study the ripening of seeds with succulent coverings, the fruits—the proper subject of this article—we may undertake to compare fruit-ripening with vegetable nutrition on the one hand, and with animal nutrition on the other hand, as follows:

Fruit-ripening, then, coincides with vegetable nutrition in acting with the same substances, and coincides with animal nutrition in moving in the same direction.

To inquire, now, somewhat in detail, into the more obvious of the changes which constitute fruit-ripening, we may examine the proportion and formation of the following five classes of

 1. Sugars (starches). 2. Pectous substances and gums. 3. Acids, tannin, and other glucosides. 4. Ethers. 5. Alkaloids.

The analyses of fruits hitherto reported have mostly been made by European chemists. The fullest reports of ripe fruits, upon which I am in good part dependent, were made by Fresenius, from analyses under his direction, nearly twenty years ago, and represent the fruits of the Rhine district, obtained at Wiesbaden.

1. —The prevailing sugar in fruits is glucose (dextrose),