1916] AGRICULTURAL BOTANY. 131 



far the activities of oxidizing enzyms depend upon tlie age of the flower and 

 other factors, such as illumination. 



It is stated that peroxidase reactions of certain species and varieties of Iris 

 are similar, though the distribution and quantity of anthocyanin may be very 

 dJiferent. Peroxidase reactions are well marked in the Xiphion group, variable 

 as regards distribution in the Apogon group, and absent in the Pogoniris group. 

 Active peroxidase increases more or less in Iris flowers kept in darkness, and 

 the production of organic peroxid was recorded in one case. Owing presumably 

 to complications introduced by inhibitors, it is impossible in Iris to correlate the 

 distribution of peroxidase and anthocyanin, the latter frequently appearing in 

 the absence of the former in an active state. 



The formative starches of green leaves and their utilization, F. W. Neger 

 (NaturtvissenscJiaften, S (1915), No. 31, pp. 401, 408). — Discussing the carbo- 

 hydrate content of green leaves, the time at which it is greatest, and the possi- 

 bility of its more economical utilization, the author notes some findings reported 

 by former investigators or obtained by himself. 



Observations on the starch content of several plants show that in these cases 

 the maximum, while it may occur at different hours, generally falls in the after- 

 noon or evening. The starch content of leaves and its transfer appear in most 

 cases to be diminished under very high temperatures. The practice of gather- 

 ing vegetables late in the afternoon is most profitable only when the accumu- 

 lation of carbohydrates during this period is not too largely neutralized 

 by its transfer to the stems before its sale and utilization the next day. 



In regard to the removal of the leaves, which is suggested, starches tend to 

 change into sugars, due to the presence of a ferment in the leaves, the activity 

 of which seems to bear some rather intimate relation to respiration. It is sus- 

 pended in irrespirable gases, but is resumed after removal therefrom if they are 

 of a nonpoisonous character. In case of leathery leaves or, in particular, those 

 of evergreens, the stores of carbohydrates are often larger, being the net accu- 

 mulations of several days. The mobility of starch is much less in evergreen 

 than in deciduous leaves. It is stated that the foliage of conifers contains, 

 particularly in autumn and spring, large quantities of starch in a stable 

 condition. 



The starch economy of green plants, F. W. Negkr {Naturiv. Ztsclir. Forst u. 

 Landiv., 13 {1915), No. 8-9, pp. 370-380).— This is a more detailed account of 

 the facts summarized in the article noted above. 



Starch formation in underground portions of herbaceous plants, J. d'Arbaxj- 

 MONT (Bui. Sac. Bat. France, 61 (1914), No. 5-6, pp. 347-351).— The author has 

 followed the woi-k of Guilliermond (E. S. R., 28, p. 524) in the study of starch 

 formation as related to leucoplasts. He states that besides the concentric de- 

 velopment of the starch grain there may be noted two other phases, namely, a 

 peripheral phase developing centripetally and one developing both centripetally 

 and centrifugally at the same time from the periphery and the center, respec- 

 tively. These and related phenomena ai'e discussed as noted in different plants. 



Humus as a source of carbon for green plants, M. Molliakd (Rev. Gen. Bat., 

 27 (1915), No. 313, pp. 1-9). — The author gives an account of experimentation 

 from which he concludes that humus can not be considered a direct source 

 of carbon for green plants to any appreciable extent. 



The role of the ash constituents in living plants, I, M. A. Egorov (Zhur. 

 Opytn. Agron., 16 (1915), No. 4, pp. 270-280). — In a preliminary account of the 

 relation between ash constituents and maturation it is stated that oats remain 

 green after being desexed. It is thought that the direct cause of maturation in 

 the Graminese, so far as that is manifested in the yellowing of the plant, is the 



