828 EXPERIMENT STATION EECORD. 



series of experiments. Decreased illumination is lield to be an important factor 

 in all tliese anomalies. 



The relations between oxidation ferments and respiration in plants, E. W. 

 Schmidt {Naturw. Wchnschr., 26 (1911), No. 17, pp. 251-26^; ahs. in Bot. 

 Centbl., 119 {1912), No. 20, pp. 492, 493).— This is a critical reA'iew of recent 

 articles on respiratory ferments, etc., particularly those of W. Palladin and his 

 school. 



Tannin content and starch formation in woody growths, A. Renvall {Bot. 

 Centhl., Bcihefte, 28 {1912), 1. Abt., No. 2, pp. 282-306) .—The author made a 

 study of numerous trees as to the relation of their tannic acid content in the 

 winter to their development of starch in the following spring. 



It was found that in those structures deficient in tannin and in those trees in 

 which it appeared wholly wanting there was no corresponding lack of starch 

 development in spring. From a study of the details observed the conclusion is 

 drawn that tannin in the cases studied can have little or no 'significance as a 

 transformation product, or as an agent influencing transformation, so far as 

 starch is concerned. Further studies are promised on starch transformation in 

 leaves which remain green during the winter. 



Some conditions influencing the fixation of nitrogen by Azotobacter and 

 the growth of the organism, Florence A. Mockebidge {Ann. Bot. [London], 

 26 {1912), No. 103, pp. 871-887). — The author's investigations on the production 

 of a vigorous culture of Azotobacter led to the following conclusions : 



The presence in the medium, as a neutralizing agent, of an excess of calcium 

 or magnesium carbonate or of basic slag, is more advantageous than that of 

 sodium hydrate. The presence of sodium salts is unnecessary and depressing. 

 A good growth being once obtained, the yield of nitrogen appears to be practi- 

 cally proportional to the food supplied. The most active fixation occurs during 

 the first week, being thereafter depressed, apparently, by the accumulation of 

 the products of vital activity. It appears that a proportion of 0.4 per cent of 

 basic slag has the most beneficial effect upon the activity of the organism, 1 per 

 cent showing a second and lower maximum. It is thought probable that the 

 iron and manganese present in the slag exert, in addition to a neutralizing 

 effect, tonic influences upon the organisms, these reaching maxima at 0.4 and 

 1 per cent, respectively. 



The formation and physiological significance of the root nodules in the 

 Podocarpineae, Ethel R. Spbatt {Ann. Bot. [London], 26 {1912), No. 103, pp. 

 801-814, pJs- 4)- — The author reports on a series of investigations made with 

 Podocarpus, Microcachrys, Dacrydium, Saxegothsea, and Phyllocladus, all pos- 

 sessing root nodules. These nodules are claimed to be modified lateral roots, 

 perennial and usually unbranched. 



Pscudomonas radicicola penetrates by way of a root hair to the cortical cells 

 of the root, where it pi'opagates itself, infecting the meristematic tissue and 

 stimu'lating the development of a nodule wliich, when mature, is traversed for 

 about half its length by a small stele. Nodules of the Podocarpine.-e differ from 

 those of all other nonleguminous plants in that there is no differentiation of a 

 meristematic zone in the cortical tissue. Many cortical cells of root and nodule 

 eventually become water stoi'age cells, some containing bacteria in a quiescent 

 state during the winter. The bacteria form a very definite zooglea in the cells, 

 slime threads passing from cell to cell. 



The bacteria isolated from the nodules of the Podocarpineie are found to be 

 identical with P. radicicola obtained from those of the Ijeguminosre, Cycadacese, 

 Elseagnacere, Alnus, and Myrica ; capal)le of assimilating atmospheric nitrogen; 

 and presumably of benefit to the Podocarpineae. 



A bibliography is given. 



