208 THE AMERICAN NATURALIST.  [V0L XXXII. 
BOTANY. 
Ripening of Fleshy Fruits. — Mr. C. Gerber contributes a paper 
of 280 pages on this subject to Ann. d. Sci. Nat. Bot., 8th ser., tome 
iv, nos. 1-6, 2 pl. He studied the behavior of many fruits, — 
apples, pears, peaches, plums, grapes, oranges, lemons, melons, med- 
lars, loquats, persimmons, bananas, etc. In the space of a short 
review it is possible to mention only a few of the many interesting 
facts set forth. Some of the changes which take place in the ripen- 
ing of fruits are: 
(1) The acids, malic, tartaric, citric, are partially used up in the 
formation of carbohydrates. 
(2) The tannin disappears by complete oxidation, without forming 
any carbohydrates. 
(3) The starch is transformed into sugar. 
(4) The saccharine substances partly disappear by oxidation. 
Mr. Gerber finds that the odors of certain fruits are due to the 
asphyxiation of the cells, alcohols and volatile acids (acetic, formic, 
etc.) being formed and these uniting to form agreeable ethers. The 
asphyxiation of the ripening fruits is due to the development of pec- 
tin, which swells, closes up the intercellular spaces, and shuts out 
the air. If the fruits are then kept at a sufficiently high temper- 
ature, so that the life processes of the cells go on rapidly, more oxy- 
gen is necessary than can filter through the swollen tissues and that 
in the sugar is drawn upon, but only after the tannin has entirely 
disappeared, z.e., the sugar is broken down with the formation of 
acids and alcohols (and subsequently of ethers) and the liberation 
of carbon dioxide. At lower temperatures the cells of the fruits are 
able to get the small amount of oxygen required for their life proc- 
esses from the air, and consequently no volatile acids, alcohols, or 
ethers are formed. This is why such fruits as persimmons an 
bananas are destitute of odor when ripened in cool places. The 
facts of respiration are as follows : 
(1) Sweet fleshy fruits in certain phases of their development lib- 
erate in a given time a volume of carbon dioxide greater than the 
oxygen absorbed, so that the respiratory quotient (a) is greater 
than unity. 
(2) This special respiratory quotient has a different origin and 
progress, according to the stage of ripening and the chemical prin- 
ciples in the fruits. Two kinds of quotients superior to unity are 
