BOTANY. 1025 



being' parasitic on the roots of these plants it also attacks cabbage, 

 rape, and shepherd's purse. All attempts to cause it to establish itself 

 on watermelon, clover, wheat, and potatoes have failed. 



Brief notes are giveu on the grass plats planted at the station to test 

 the quality, yield, hardiness, rate of growth, etc., of different species of 

 cultivated and native forage plants. 



Mention is also made of cooperative experiments with the Division 

 of Forestry of this Department in which the rate of growth, quality, 

 etc., of trees of the same species grown from seeds collected in different 

 parts of the United States arc to be tested. 



Investigations on the ripening of fleshy fruits, 0. Gerber ( Ann. 

 Sci. Nat. Bot., 8. ser., 4 (1897), No. 1-6, pp. 1-280, pis. 2).— The author 

 has made a study of the changes taking place in fleshy fruits during 

 their ripening. The principal subjects of the extensive experiments 

 were apples, grapes, and oranges, representing the malic, tartaric, and 

 citric acid groups; the Japanese persimmon, representing the tannin- 

 contaiuiug fruits; and the banana as a type containing an abundance 

 of starch. In addition to these, comparisons were made with alkekengi, 

 mangoes, apricots, peaches, pears, plums, melons, etc. Culture experi- 

 ments with molds were maintained to verify the conclusions relative to 

 transformations by the fruits. Whatever substances were noted in the 

 fruit the same were added to the culture media in which Sterigmato- 

 cystis nigra was grown, and parallel experiments were conducted often 

 with identically the same results. The gaseous exchange between the 

 fruits and air was noted at different temperatures ranging from 0° to 

 30° 0., such temperatures occurring either during the day or the night 

 at the time of the normal maturity of the fruit. As far as possible the 

 experiments were conducted with whole aud sections of the fruits at 

 different degrees of ripeness on and off the tree and during the mellow- 

 ing of the fruit. After noting the respiration the fruits were subjected 

 to chemical analysis to determine the presence of acids, tannin, starch, 

 sugar, etc. 



Contrary to the respiration of ordinary plants, fleshy sweet fruits, 

 during a considerable portion of their development, give off a greater 

 volume of carbon dioxid than the amount of oxygen taken up. The 

 author considers the respiratory quotient under two heads — the acid 

 quotient due to the presence of acids, and the fermentation quotient, by 

 which is meaut the respiration resulting in the production of alcohol, 

 through an insufficient quantity of oxygen brought to the cells. These 

 two respiratory quotients differ in respect to time and temperature at 

 which each is most active, their value and intensity, and, by their 

 chemical results, the fermentation quotient indicating the formation of 

 alcohol and essential oils, while nothing comparable is indicated by the 

 acid quotient. 



The principal modifications found during the maturing of the fruits 

 are shown in the chemical changes observed in the acids, tannins, 



