AGRICULTURAL BOTANY. 823 



aims of the geneticist are (1) to observe the origin of new and distinct forms, 

 the genetic relationship of which must, therefore, be known, (2) to determine 

 the conditions which brought these forms about, so as to be able to produce 

 them at will, and (3) to study their hereditary behavior and their morpho- 

 logical and chemical characteristics in order to provide a basis for sound de- 

 duction in regard to the genetic relationships of organisms. All of these aims 

 are declared to have been realized in some measure as a result of the recent 

 activity in the study of genetics. This view is upheld in a synthetic discussion 

 of the work and opinions of various authors. 



Subdivisions should extend as far as any one finds necessary, since the 

 geneticist needs to have definite designations for much smaller groups than the 

 ecologist or the morphologist is likely to be interested in. Manuals should 

 supply the needs of either class. 



The genetic relationship of parasites, F. D. Keen (Amer. Jour. Bot., 2 

 {1915), Xo. 3, pp. 116-131). — This discussion lays emphasis on parasites as an 

 aid in determining specific and generic relationships in their hosts. This is 

 illustrated with examples drawn from the author's previous study (E. S. R., 

 27, p. 424) on hosts as paralleling parasitic species of the genus Gymnosporan- 

 gium. 



Systematic relationships among the nodule bacteria of some legumes, II. 

 IVRUGEii {Beitrdge ziir Artcnfrage dcr Knollchenbakterien ciniycr Lcguminoscn. 

 Inaug. Diss., Univ. Leipsic, 1913, pp. 56; abs. in Ztschr. Bot., 6 (1914), No. 9, 

 pp. 782, 783). — The author has been able by cultivation, it is claimed, to separate 

 Bacillus radicicola into four groups according to the legumes with which they 

 are associated, namely, Liipinus perennis, L. angustifolius, L. luteus, and 

 Ornithopus sativns; Vieia satii-a and Pisum arvense; Medicago lupuUna, 31. 

 sativa, Melilotus albus, and Trigonella fcenumgrwciun; and Lotus uliginosus, 

 AnthyUis vulneraria, and Tetragonolohus purpurea. 



No relationship was noted between T'. sativa and V. faba in this regard, and 

 Phascolus vulgaris, Trifolium pratense, Onobrychis sativa, and Soja hispida 

 showed no relationship among themselves or with the others studied in this 

 respect. 



Problems in soil bacteriology, J. G. Lipman {Abs. hi Science, n. ser., 42 

 {1915), No. 1079, p. 3i6).— Attention is called to the desu-ability of a further 

 study of a number of problems in relation to soil bacteria, among them the 

 location of species, their associative and antagonistic relations, their role in 

 the formation of humus, and the effect of temperature, moisture, aeration, and 

 other factors influencing their activity in the soil. 



The effect of certain organic soil constituents on the fixation of nitrogen 

 by Azotobacter, B. Williams {Abs. in Science, n. scr., 42 {1915), No. 1079, 

 pp. 320, 321). — This paper gives the results of a study of the effect of various 

 organic compounds, such as are likely to be found in soils, on the growth of 

 Azotobacter. 



The results indicate that the fixation of nitrogen by Azotobacter is only 

 slightly influenced by the compounds investigated. Hydroquinon and salicylic 

 aldehyde were the most toxic of any compounds studied, while esculin, quinic 

 acid, and borneol gave marked stimulation to the gi'owth of the organism. As 

 a rule, the effects of the compounds on the micro-organism were not in accord 

 with what has been reported of their action on higher plants. Concentrations 

 which are fatal to certain higher plants only slightly depressed fixation. Such 

 compounds as nicotin, picolin, guanidin, and skatol exhibited toxic properties 

 similar to those usually ascribed to these substances, though caffein stimulated 

 the growth of the organism. Many of the nitrogenous compounds used, which 

 have been reported as beneficial to higher plants, had a markedly depressive 



