784 EXPERIMENT STATION RECORD. 



"(2) Under abnormal conditions, when the stomatii or intercellular spaces are 

 blocked and the surrounding tension of carbon dioxid is great enough, ]tassage of 

 carbon dioxid by osmosis through the cuticle may taiie j)lace. 



"(3) That such closure of stoniata as is lield to take place in darkness does not 

 prevent the distribution of gas exchange closely agreeing with that of the stomata. 



"(4) That the exhalation of carbon dioxid in bright light by a leafy shoot in Gar- 

 reau'e well-known experiment is not the expression of any physiological truth for 

 the leaf, bnt only due to the imperfections of the conditions; to the presence of 

 immature parts, or of tissues not sufficiently green or not fully illuminated. Mature 

 isolated green leaves fully illuminated assimilate the whole of their respiratory car- 

 bon dioxid and allow none to escape from them." 



The bacteria of the root tubercles of Leguminosee, M, Gonneb- 



MANN [Landic. Ja]irh.,2:> (/.S.vi), Xo. 4 and 'j, pj)- 649-071). — The Hutlior 

 has sought by means of pure cultures; soil iuvestigatious, and iiiocula- 

 tion experiments to ascertain the probable number of forms of bacteria 

 capable of forming tubercles on the roots of leguminous plants. The 

 methods emi)loyed by the author are described very minutely. Plate, 

 gelatin, and potato cultures were made of all forms found in the tubercles 

 of. Luinnns alhus, L. angustifolhis, and L. luteus, and the winter soil was 

 carefully examined to learn how the organism passes the winter. He 

 found in his cultures several forms of Bacillus and Micrococcus, and 

 claims that those bacteria forming tubercles on the roots of legumes 

 are spore forming, and in this way pass the winter in the soil. 



From his experiments the author thinks that there is not so great a 

 necessity for the presence of bacteria for nitrogen assimilation as is 

 sometimes claimed, and that the relationship between the plant and the 

 organism is often one of parasitism rather than of symbiosis. 



The author concludes that (1) the tubercles of Leguminosw are not 

 formed by a single specific bacterium, but that in different localities are 

 to be found different organisms capable of producing them; (2) tlie 

 Y-formed specimens, the so-called bacteroids, are very complex while 

 in symbiosis with the plant, but later upon the dissolution of the tuber- 

 cles they separate into simi)le bacilli, and as such they may be found in 

 the surrounding soil. In the spring they enter the plants and form by 

 their growth into new Y-shaped bodies; (3) the symbiotic relationship 

 is not yet completely established, since the tubercle bacteria alone can 

 not make the free nitrogen available for the plant, but it seems more 

 probable that the plant itself without symbiosis can take up and assim- 

 ilate free nitrogen; the bacteria, however, may assist the plant in con- 

 tributing to its higher nitrogen content. Further, it is shown that in 

 spite of the presence of bacteria the plants do not take up any greater 

 nitrogen content. From many recent experiments it is shown that not 

 only a symbiotic but also a parasitic relationship exists between the 

 plants and their bacteria, also that the effect of the bacteria and the 

 method of nitrogen assimilation are not well known. 



On the presence of alumina in plants and its distribution, 

 Berthelot and Gr. Andre [Compt. Rend., 120 {1895), ¥o. 6, pp. 288- 

 290). — As a contribution to the question of the existence and proportion 

 of alumina in plants the following determinations, among other ^ata, 



