134 EXPERIMENT STATION RECORD. 



ascribed to the arrest of the formation of the allialoid when the plant is grown 

 in darliuess. 



Heliotropism in radium illumination, H. Molisch {Sits'ber. K. Akdd. Wiss. 

 [Vienna], Math. Naturw. El., 120 (1911), I, No. 4, pp. 305-318, flgs. 5; abs. in 

 Ztschr. Bot., 4 {1912), No. 2, p. 151). — This is a continuation of worlc taken up 

 several years ago by the author on radium and heliotropism of plants (E. S. R., 

 17, p. 752) in which only negative results were obtained, owing presumably to 

 weakness of the radium preparation employed. 



He now concludes that radium of strong illuminative power exposed at short 

 distances is capable of producing in heliotropically very sensitive plants a 

 positive tropism. This is true of the young seedlings of oats {Arena sativa) 

 and vetch (Vicia sativa), but barley (Hordcum vulgare) and sunflower (Heli- 

 anthus annuus) are not sufficiently sensitive to respond to radium illumination 

 so far as tried. The a, /3, and y rays seem to check the longitudinal growth of 

 the plants, also to shorten the period of spontaneous nutation, limit the synthesis 

 of anthocyanin, and in some cases produce other injurious effects on plants 

 which are A-ery sensitive to its action. 



Investigations on Mvicorinese and their relations to soil, O. Hagem ( Vidensk. 

 Selsk. 8kr. [Christiania'i, Math. Naturv. KL, 1910, No. 1,, pp. 152; ahs. in 

 Inte7'nat. Inst. Agr. [Rome'], Bui. Bur. Agr. Intel, and Plant Diseases, 2 {1911), 

 No. 11-12, pp. 2. '(75-2 477). — Studies by the author and others have shown about 

 30 species of Mucorineje present in the soil and that they constitute an important 

 element in the fungus flora of soils. Most of the species identified belong to 

 the genera Mucor, Absidia, and Zygorbynchus. The distribution of the species 

 seems to vary with different soils, those in cultivated soils differing from the 

 species present in the soil of coniferous woods. While the relation of the 

 Mucorine?e to mycorrhiza has not been established, it appears that there is a 

 close relationship between the species present in the soil and those found 

 occurring as mycorrhiza on roots. Both obligate and facultative parasites are 

 found among these soil molds, but in most soils the facultative parasites pre- 

 dominate. Some species seem to be obligate parasites on higher fungi, as the 

 agarics, and most of these belong to the genera Spinellus, Dicranophora, and 

 Sporochinia. 



The nitrogen, carbon dioxid, acid, and temperature relations of the different 

 groups were studied. Only a few species were found to have any considerable 

 effect on the nitrogen balance of soils through their action on nitrites and 

 nitrates. Their importance, so far as the nitrogen balance is concerned, depends 

 on the transformation of the ammoniacal nitrogen into a stable form which is 

 useless to higher plants. The aminic and amidic nitrogen of the various organic 

 substances in the soil is transformed by some of the species into ammoniacal 

 nitrogen, a part of which is transferred into stable forms, while the other part 

 circulates through the soil and can be utilized by higher plants. 



The investigations showed that the Mucorinete in general, and especially the 

 soil forms, could not attack many carbon compounds, particularly cellulose 

 and hemicellulose, although they could change various saccharin and pectin 

 substances. 



The temperature limits for the growth of most species lie between 7 and 33° 

 C, with optima of from 20 to 25°. 



An extended bibliography is given. 



The) slime or gum of Rhizobium leguminosarum, R. Greig-Smith (Centbl. 

 Bakt. [etc.], 2. Abt., 30 {1911), No: 21-24, pp. 552-556, fig. i).— This is a short 

 account of work, the results of which were previously published elsewhere 

 (E. S. R., 18, p. 1031). The author here describes briefly his methods of obtain- 



