AGRICULTURAL BOTANY. 225 



The conclusion is reacliecl that the bulbs from some orchids contain a sud- 

 stance of a fungicidal nature that may be considered comparable to a diastase. 

 It is readily diffusible and is destroyed at a temperature of 55° C. The action 

 is considered specific and is held to confirm the hypothesis of the author i-egard- 

 ing the symbiosis with mycorrhizal fungi, while protecting the main body of 

 the plant against invasion (E. S. R., 22, p. 722). 



Effects of Roentgen rays on micro-organisms and ferments, H. GtJNTHEB 

 (Sitzbcr. Xaiurhist. Ter. Prcu.ss. Rhciniande u. Westfalcns, 1910, No. 1, Sect. B. 

 pp. 11, 12; abs. in Bot. Centbl, 116 {1911), No. 24, p. 611t).—K brief note review- 

 ing the literature on this subject, most of which is declared to show negative 

 i-esults. 



Nitrogen-fixing bacteria in leaves of Eubiaceae, F. C. von Faber {Adv. 

 print from Bui. Dept. Afjr. Indes Nccrland., 191 1, Xo. //(?, pp. 3). — The author 

 presents a preliminary report of investigations in progress, from which he is 

 able to give results and conclusions in substance as follows: 



The plants of this group bearing these bacteria may be outwardly known by 

 peculiar knotty thickenings of the leaves filled with bacteria. Garden species 

 so affected are Pavetta indica, P. lanceolata, P. angustifolia, P. zimmerman- 

 niana, and Psychotria hacteriophila. Bacteria are found in. the growing points 

 and from there supposedly extend with the growth of the i)lant, being found 

 in the buds, flowers, fruit, and seeds. In the young bud leaves the stomata 

 open alniormally early and the massed bacteria press into the leaf interior, 

 loosening the cellular structui'e and causing characteristic cytological changes 

 which result in the production of a characteristic bacterial tissue. In this a 

 considerable number of starch grains appear, supposedly to serve nutritive 

 puiT)oses for the bacteria. 



Already bacteria have been isolated by culture from P. indica and Psychotria 

 hacteriophila, one species only from each. The bacteria of Rubiace;Te seem to 

 .show great similarity among thexuselves and may be adapted forms of one 

 original species. The author thinks that these bacteria play the important 

 role in the life of the plants in which they live of fixing atmospheric nitrogen, 

 and claims that this conclusion is supported by the experimental evidence thus 

 far obtained. This work of fixation is thought to be limited to the bacterial 

 leaf galls where the bacteria are present in largest numbers and where the 

 nitrogen is present mainly in the form of protein. 



Nitrogen fixation by fungi in relation to nitrogen nourishment, G. Stahel 

 {Jahrh. Wiss. Bot. [Pringsheinh], Jf9 {1911), No. J,, pp. 519-615; abs. in Bot. 

 Centbl., 119 {1912), No. 1, pp. 9, 10). — These exi^eriments were undertaken for 

 the purpose of finding, if possible, new cases of nitrogen fixation by fungi and 

 of studying the relation of nitrogen assimilation to nitrogen content in their 

 food supply. 



The organisms belonged for the most part to the so-called imperfect fungi, 

 54 species being investigated. In case of a nutrient solution containing 0.0001 

 per cent of nitrogen, it was found possible to divide the fungi into groups, the 

 first of which, containing 25 species, showed no growth but much oil and was 

 entirely sterile ; the second, comprising 22 species, showed better but slight 

 growth and considerable oil, and was almost or quite sterile; a third group of 

 5 species showed relatively good growth, very good fruiting, and but little oil. 

 Of the 9 species which showed nitrogen fixation 4, it is claimed, had not before 

 been credited with that power. These are Botrytis cinerea, Bispora moHnioides, 

 Epieoccum purpurascens, and Melanomma sp. Three fungi were found to con- 

 tain nitrogen as compared with the amount in the nutrient solution In the ratio 

 of 1 : 1, while one showed a ratio of 1 : 4. These ratios, it is stated, tend to rise 

 with an increase of nitrogen content in the substratum. 



