FIELD CROPS. 327 



peroxidase. Pure peroxidase, it is claimed, does not give auy color reactiou 

 witli aloin, but most plants contain substances tliat favor the color test for the 

 presence of peroxidase. 



In regard to the respiratory pigments, they were found to vary with differ- 

 ent plants. In some plants sodium chlorid was found to stimulate the develop- 

 ment of chromogens, but in wheat seedlings and etiolated stems of beans they 

 were retarded. Emulsin is said to hasten the appearance of respiratory pig- 

 ments in wheat embryos, but to checlv them in bean seedlings. Sodium chlorid 

 had a retarding effect on the development of resiDiratory pigments in some 

 plants, but stimulated them in other cases when used in conjunction with 

 emulsion. 



On the presence of a glucosid in the leaves of pears, and investigations of 

 its occurrence in the trunli and roots, E. Boukquelot and Mile. A. Fichten- 

 HOLz (Conipt. Rend. Acad. 8ci. [Paris], 153 {1911), No. S, pp. 46S-471). — In a 

 previous publication (E. S. E., 24, p. 31), the authors called attention to the 

 occurrence of a glucosid, which they determined as arbntin, in the leaves of 3 

 varieties of cultivated pears. Since that publication they have continued their 

 observations and studied a considerable number of varieties of cultivated as 

 well as wild pears and found the arbutin present in the leaves of all. It was 

 also found present in the tips of the branchlets, in tlie bark of the trunk, and in 

 the roots, but in the latter two organs it had nearly disappeared. 



Carbon dioxid at high pressure and the artificial ripening of persimmons, 

 F. E. Lloyd (Science, n. set:, 34 {1911), No. 887, pp. 92^-928) .—The author 

 summarizes some investigations on the loss of astriugency of persimmons, dates, 

 and similar fruits, and claims, on the basis of his investigations, that the loss 

 of astringency during the process of ripening is due to the union of tannin with 

 an associated colloid of a carbohydrate nature. 



He reports experiments with the artificial ripening of persimmons in carbon 

 dioxid and states that under increased pressure of carbon dioxid the process 

 of ripening is hastened, so that with a pressure of 15 lbs. the time required may 

 be reduced from 6 or 7 days, the time required under normal pressure, to less 

 than 2 days. 



Evidence is presented that at the time of ripening an enzymatic agent is at 

 work aiding in the coagulation. 



A manual of poisonous plants, II, L. H. Pammel {Cedar Rapids, Iowa, 1911, 

 pi. 2, pp. ¥+153-977, pis. 15, figs. 500). — This is the second portion of a manual 

 of poisonous plants, chiefly of eastern North America, with notes on economic 

 and medicinal plants (E. S. R., 24, p. 384). The author includes all species of 

 plants that in any way produce injury to man or animals, although many listed 

 have very important uses that more than compensate for their injurious proper- 

 ties. A catalogue of the poisonous plants of the world compiled from various 

 sources is given, and the work is concluded with a comprehensive bibliography 

 of poisonous plants, compiled by Miss Harriette S. Kellogg, more than a thou- 

 sand papers being listed. 



American medicinal leaves and herbs, Alice IIenkel {U. S. Dcpt. Agr., 

 Bur. Plant Indus. Btil. 219, pp. 56, figs. 36) . — This bulletin gives a description of 

 36 species of plants which furnish leaves and herbs for medicinal use, 15 of 

 which are official in the United States Pharmacopoeia. 



FIELD CROPS. 



The influence of different degrees of soil moisture content and soil com- 

 pactness and of different fertilizer applications on root development in wheat 

 and barley during the early stages of growth, R. Polle (Jour. Landw., 58 

 (1910), No. It, pp. 297-3IfJt). — Chevalier barley and Bordeaux wheat were grown 



