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:
In Vegetable Nutrition. |
In Fruit-Ripening. |
In Animal Nutrition. | ||
| 1. Oxygen is given to the air. | Oxygen is taken from the air. | Oxygen is taken from the air. | ||
| 2. Carbonic acid is taken from the air. | Carbonic acid is given to the air. | Carbonic acid is given to the air. | ||
| 3. The service of plant-green is required. | The service of plant-green is dismissed. | |||
| 4. Simple compounds are changed to those more complex. | Complex compounds are changed to those more simple. | Complex compounds are changed to those more simple. | ||
| 5. The expended power of the sun is stored. | The stored-up power of the sun is expended. | The stored-up power of the sun is expended. | ||
| 6. Heat is absorbed. | Heat is liberated. | Heat is liberated. | ||
| 7. The changes represent reductions and syntheses, difficult to the chemist, and hindered by atmospheric conditions. | The changes represent combustions and dissociations, and are mostly favored by atmospheric conditions. | The changes represent combustions and dissociations, and are mostly favored by atmospheric conditions. | ||
| 8. Opposed to fermentations, and to other changes classed under the term organic decomposition. | The changes include a great number of distinct fermentations, some of which are spontaneous in the air, or occur in cooking food. | Some of the changes are allied to fermentations, but are mostly not liable to occur without the living body. | ||
| 9. The important compounds of the vegetable kingdom cellulose, starch, sugar, and many acids and other products are common to the fruit and other parts of the plant. |
Only a few animal products are found in the vegetable kingdom. | |||
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 Fruit-Products:
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. Sugars.—The prevailing sugar in fruits is glucose (dextrose),
