NOTES AND ABSTRACTS. 



653 



Melon Aphis, How to Combat the. By M. H. Swenk {U.S.A. 

 Exp. Stn., Nebraska, Bull. 34; June 1911; 1 iag.).— This aphis 

 (Aphis gossypii Glover) is a very injurious pest to cucumber and 

 melon plants. The loss of crops from it in Nebraska alone amounts 

 to several thousands of dollars annually. The same aphis is a common 

 pest of cotton in the Southern States, and occurs in the West Indies, 

 Mexico, Brazil, South Africa, and Australia. It is probably of tropical 

 origin. 



Spraying with Black-Leaf Tobacco extract 1 to 50 parts of water, 

 and fumigation with carbon bi-sulphide, are recommended. — V. G. J. 



Mint Cultivation. By J. Knight (Jour. Dept. Agr., Victoria, x. 

 p. 361; June 1912). — Directions for starting and maintaining planta- 

 tions of black mint (Mentha piperita). — F. J. C. 



Mycotrophic Plants, Nutrition of. By H. Weyland (Jahrh. f. 

 wiss. Bot., Bd. li. pp. 1-80; 1912). — In this paper a comparison is 

 instituted between the nutrition of ordinary green plants and those 

 which obtain their food more or less completely from organic sources. 

 The author's chief method is that of microchemical testing for urea 

 and allied nitrogenous substances, which are produced by fungi in 

 their metabolism. He finds that urea occurs in a number of myco- 

 trophic flowering plants — plants which obtain more or less of their food 

 by the aid of a root-inhabiting fungus (mycorrhiza) — and especially in 

 the saprophytic orchids (Listera, Ophrys, Gy'mnadenia, Neottia, 

 Epipactis, &c.). On the other hand, urea was not present, at any 

 rate in recognizable amount, in a number of other plants with 

 mycorrhiza, nor in the Leguminosae (which may be explained by the 

 fact that these plants assimilate nitrogen from the amosphere by 

 means of their tubercle bacteria) ; while urea was found in a few 

 non -mycotrophic plants growing in rich humus — in this case, it was 

 probably absorbed directly from the soil. The absence of urea from 

 plants with external (ectotrophic) mycorrhiza is explained by the 

 author on the ground that the relationship between fungus and higher 

 plants in such cases is not so intimate as in the case of the orchids 

 mentioned above and other plants with internal (endotrophic) 

 mycorrhiza. 



Weyland also investigated the occurrence and distribution of 

 phosphorus, potassium, and calcium in various autotrophic and 

 mycotrophic plants. He found the fungal hyphae in the roots 

 of the saprophytic orchids, and the tissue of the roots themselves, 

 particularly rich in phosphorus, as is also the case with the bacterial 

 nodules of Leguminosae. The roots of saprophytic orchids are also 

 strikingly rich in potassium and in calcium — the abundance of the 

 latter metal suggests that it serves for the neutralization of the acids 

 produced by the mycorrhizal fungus. — F. C. 



New Mexico, Plant GeOg'Paphy of. By J. E. Watson (Bot. Gaz. 

 vol. liv. pp. 194-217; Sept. 1912; 7 figs.).— The northern half of 



