The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. "1 Substrate-2 0 quotient is the value obtained firom the ratios Voltbne of COg produced Volume of Og consumed The invostigabions of Maze' and Georgi and Vi'ilson furnish information concominf^ tho total gaseous exchango of culturoa of rhizobia over long porioda of incubation. No data are available, hoiviBver, conoominc the cliangos in tho respiratory qxAotients of the organisms during tho grovrbh period.