G34 EXPERIMENT STATIOiST PvECORD. [Vol.43 



ono thin primary layer. These are, therefore, rings of nightly growth. Cer- 

 tain abnormal appearances indicate that the cellulose wall may grow for a 

 time without being in full contact with the ectoplasm. 



Artificial budding' of roots, H. IMoliscii (Sitzber. K. Akad. Wiss. [Vienna], 

 Math. Natiinr. KL, 126 {1911), I, No. 1, pp. 3-13, pis. 2; abs. in Intematl. Inst. 

 Agr. [Rome], Intematl. Rev. Sci. and Pract. Agr., 9 (1918), No. 11, pp. 1302, 

 1303; also in Gard. Chron., 3. set:, 66 {1919), No. ITU, pp. 227, 228).— The ques- 

 tion regarding a winter resting period for subterranean, corresponding to that 

 of aerial, parts was investigated. Tlie author employed for this purpose 

 freshly cut branches one to three years old of Salix, Populus, Philudelphus 

 coronurius, and Viburnum opulus, all of wliich produce I'eadily adventitious 

 roots. These plants were subjected during September to November to forcing 

 by such agents as hot water and smoke of tobacco and paper, exposed for 

 an hour or two to the open air, and placed in a greenhouse ut I'i to 20° C. 

 or in a tliermostat at 25° (77° F.). 



The tobacco smoke exposure during 24 hours caused earlier leaf fall and 

 also caused adventitious roots to appear a few weeks later, as in case of ex- 

 posure to paper smoke for 48 hours and to warm water (30°) for 12 hours. 

 Controls showed a few or no adventitious roots. 



The conclusion readied is that during a certain period the roots tend to rest 

 from their functions. This period does not always depend upon the existence 

 of unfavorable factors, but is very often independent. 



Old age in perennial plants, [H. M. Benedict] {Qard. Chron., 3. ser., 66 

 {1919), No. nil, p. 190).— To the contribution previously noted (E. S. R., 34, 

 p. 222) is added liere a brief notice of observation and opinion by others bear- 

 ing on the subject. 



Studies in the metabolism of actinomycetes.— Ill, Nitrogen metabolism, 

 S. A. Waksman {Jour. Bact., 5 {1920), No. 1, pp. 1-30). — Experiments con- 

 ducted at the New Jersey Experiment Stations on the utilization of different 

 nitrogenous compounds by actinomycetes and the transformation of the sub- 

 stances due to the action of tliese soil organisms are reported. 



It was found tliat the actinomycetes do not fix atmospheric nitrogen, although 

 some colonies will develop on routine nitrogen-free media. Most species were 

 able to reduce nitrates to nitrites with the proper source of carbon, a few 

 species were able to reduce nitrates to nitrites actively with nearly all sources 

 of carbon studied, and a few others gave no reduction or only traces with 

 nearly all sources of carbon. 



The proteins and amino acids studied were found to form the best sources of 

 nitrogen for this group of organisms. Aniids were used only to a very small 

 extent. Nitrates were used fairly well in the presence of the proper source of 

 carbon. Nitrites present in small quantities in the medium were utilized well 

 by most species, particularly by those that reduced nitrates actively. Ammonium 

 salts formed the poorest sources of nitrogen with glycerol as a source of carbon ; 

 with glucose as a source of carbon, both amids and ammonium salts were 

 utilized well as sources of nitrogen, if the reaction of the medium did not tend 

 to become too acid. 



Most actinomycetes split proteins actively, as indicated by an increase of 

 the amino-nitrogen content of the medium. The organisms that produced only 

 a small amount of growth split proteins only to a very limited extent, and used 

 up only small quantities of the amino acids. The production of ammonia from 

 proteins and amino acids is not characteristic of this group, although, on con- 

 tinued incubation, considerable quantities of ammonia may accumulate in the 

 medium, as indicated by the growth of the organisms in milk or on pure proteins 

 added to sterilized soil. Many species produced soluble yellow, brown to dark 



