248 



SCIENCE 



[N. S. Vol. LI. No. 1314 



absence of combined nitrogen, a definite 

 amount of combined nitrogen was supplied 

 in tbe mediujn. Tbe full nutrient solution 

 employed contained 0.5 gr. NH^NOg per liter 

 and in tbe various series this source of nitro- 

 gen was replaced by (NHJ^SO^, CaCNOJ^, 

 asparagine, glycocoll, and urea, tbe other con- 

 stituents of the solution remaining un- 

 changed. In all the culture media nitrogen 

 as such was present in approximately equal 

 quantities and each nitrogen source was set 

 up in duplicate series, with and without 1 

 per cent, glucose. NH^NOg, CaClSTOg),, and 

 (NH^),SO^ were also used in tbe presence of 

 mannite. Tbe culture flasks were arranged 

 in series according to the medium and con- 

 nected by glass and rubber tubing for aeration 

 with ammonia-free air. Three flasks of each 

 series remained uninoculated as checks and 

 two or three flasks in each series were in- 

 oculated with the same organism. 



At the end of a growing period of from five 

 to seven months tbe cultures were analyzed 

 for total nitrogen. The Gunning-Kjeldabl 

 method was used for media free from nitrates 

 and where nitrates were present the Forster 

 modification was employed. The average of 

 the determinations of the three checks of a 

 series was taken as the nitrogen content of 

 that medium per unit weight, and any in- 

 crease in total nitrogen in the culture flasks 

 of that series was regarded as " free nitrogen 

 fixation." In the urea, glycocoll, asparagine, 

 and (NH^)„SO^ series no marked increase or 

 decrease occurred either in the presence or 

 absence of glucose or mannite. Marked in- 

 creases were foimd, however, in both WH^NOj 

 and CaCNOg), media in the presence of glu- 

 cose, the amount of fixation ranging from 6 

 to 10 mg. per culture in the 1917-18 experi- 

 ments and from 4 to 13 mg. in the 1919 experi- 

 ments. Since the initial nitrogen content of 

 the medium was but 22 or 23 mg. per culture, 

 as shown by tbe checks, this fi:sation repre- 

 sents an increase in total nitrogen ranging 

 from 17 to 55 per cent. Where mannite re- 

 placed glucose in tbe nitrate media, there was 

 no indication of fixation; and in the absence 

 of both glucose and mannite, there were only 



slight increases over the checks. Fixation 

 was not confined to any one species, appar- 

 ently all seven species showing ability to use 

 free nitrogen. The amount of fixation, how- 

 ever, varied somewhat with the different 

 species and seemed to be related to the in- 

 tensity of growth. 



One species of the 1919 experiment exhib- 

 ited what is apparently a " denitrification " 

 when grown on nitrate media in tbe presence 

 of mannite. The total nitrogen content of 

 these flasks was from 2 to 9 rog. below that 

 of tbe checks. However, the same species in 

 the presence of glucose increased the total 

 nitrogen content of the culture. There was 

 also a slight indication of denitrification with 

 this species on nitrate media in the absence 

 of both glucose and mannite. 



F. B. "Wann 



Department or Botany, 

 N. Y. State College of Ageicdltdrb 



AMERICAN PHYSIOLOGICAL SOCIETY 



REPORT OF THE THIRTY-SECOND ANNUAL 

 MEETING 



The American Physiological Society held its 

 thirty-second annual session during the holidays at 

 Cincinnati, Ohio. The scientific and business ses- 

 sions were called at the school of medicine of the 

 University of Cincinnati. Sis half-day sessions 

 were held on December 29, 30 and 31, 1919, for the 

 reading and discussion of scientific papers. In the 

 two business sessions a number of important meas- 

 ures were considered and voted, the most notable 

 of which was the establishment of a new journal 

 for the publication of periodical reviews of physio- 

 logical progress in subjects of dominant scientific 

 interest. 



The important business acts of the council and 

 of the society at the several sessions during the 

 meeting are here enumerated: 



1. The annual assessment was fixed at $1.00 for 

 the year 1920. 



2. A grant of $125 was made in aid of the pub- 

 lication of the journal, Physiological Abstracts, 

 edited by the English Physiological Society in 

 which the American Physiological Society is a 

 collaborator. 



3. Professor Donald R. Hooker, of Johns Hop- 

 kins University, was appointed managing editor of 



