HORTICULTURE. 437 



is bound to contain a wealth of varied individuals stable in their heredity and 

 giving rise to new si)ecies. 



Mass selection permitted a study of the botanical composition of collective 

 forms, the basic tyi)es of T. mtlgare Ititescens and T. cnjthrospcrmiim; the 

 division of spikes into types, showing the dominant characteristics of the fluc- 

 tuations and their variations; the determination of the wide limits of variations 

 in the form of the shape of the spike, showing that each fluctuation might be 

 considered as a sharply defined hereditary variation of an individual type. This 

 showed in the mass a variation of forms which were in reality genotypically 

 hereditary. In regard to compactness, that of T. vulgare lutescens was found 

 more stable than that of T. erythroftpcrmum, while that of T. erythrospermum 

 was more plastic. The increase of yield was greater for the less comi^act heads 

 than for the more compact ones. However, care should be taken not to lessen 

 this compactness beyond a certain degree as this causes a deterioration in yield 

 under unfavorable conditions of ripening. 



It was found that T. vulgare erythrospermum has, with all degrees of com- 

 pactness, a larger grain than T. lutescens, thus maintaining its reputation for 

 having better grain than the latter species. Average compactness gives the 

 largest grain. 



Are there wheat varieties that are more or less completely self-fertiliz- 

 ing? H. Nilsson-Ehle {Ztschr. Pflanzcnznclit., 3 {1915), No. 1, pp. i-6).— Ex- 

 periments with three varieties of wheat indicate that some varieties may 

 remain pure while other strains may become more or less cross-pollinated when 

 planted in close proximity. 



Yams (Dioscorea), R. de Noter {Les Ignames. Paris: Aiigustin Challamel, 

 1914, pp. 66, figs. iS).— Already noted from another source (E. S. R., 31, p. 334). 



Weeds on the Buzuluk Experiment Field (Samara Province) and in the 

 vicinity, S. Bazhanov {Trudy Biuro Prllcl. Bot. {Bui. Appl. Bot.), 8 {1915), 

 No. 3, pp. 276-293). — It was found that although the seed wheat contained only 

 from 1 to 2 per cent of weed seeds the crop showed as high as 12.7 per cent of 

 weeds. Investigation showed about 3,000 weed seeds per square meter to a 

 depth of 2 in. of soil in cultivated fields. Lists of weed seeds found on both 

 cultivated and fallow fields are given. 



HORTICULTURE. 



Field book of American trees and shrubs, F. S. Mathews {New York: 

 G. P. Putnam's Sons, 1915, pp. XVII +465, pis. 75, figs. 6.30).— This work con- 

 tains concise descriptions of the character and color of species common through- 

 out the United States, together with maps showing their general distribution. 

 Illustrations of leaves and fruiting parts and of typical tree barks, together with 

 several reproductions of tree studies in water-color, crayon, and pen, accompany 

 the test. 



Journal kept by David Douglas during his travels in North America, 

 1823-1827, edited by W. Wilks {London: William Wesley d Son, 1914, pp. 

 364, Pl- 1; rev. in Quart. Jour. Forestry, 9 {1915), No. 2, pp. 151-157).— This 

 journal, which is published under the direction of the Royal Horticultural So- 

 ciety, in addition to describing the author's travels in North America from 1S23 

 to 1S27, furnishes a record of various trees, shrubs, and flowers observed in dif- 

 ferent parts of the country. Particular descriptions are given of 33 species of 

 American oaks and 18 species of Pinus. A list of plants introduced by the 

 author is appended. 



Colonial plants, H. Jumelle {Les Cultures Coloniales. — Plantes OUagineuses. 

 Paris: J. B. Bailliere cG Sons, 2. rev, ed., vol. 5, 1914, PP- ^^-' fiff^- -^8) -—This 



