660 THE XODLLE ORGANISM yF THE LEiiUMIXOS.E, 



Other in\'estigators claim, us the results of experiments with 

 growing plants, that fixation onh' begins \\ hen the bacteria liave 

 become degenerated in the nodular tissue into bacteroids. As 

 long as they exist in the rod-ft)nn there is no fixation. While 

 this seems true for the plant and the bacteria, Liebscher and 

 Prazmt)wski think that Bart, radicicola can fix nitrogen in the 

 soil, and Stutzer suggests that other bacteria may assist. This is 

 quite possible, for such a fixation has been shown with other 

 bacteria and minute plants. Schloesing and Laurent* obtained 

 nitrogen assimilation with certain alga^ and mosses growing 

 upon the sui'face of soil. Winogradsk^'f separated from soil a 

 bacterium which, together with two other species, gained a 

 notable quantity of nitrogen when cultiAated in a nitrogen-free 

 glucose medium. Tliis is an interesting case of company-working 

 amonc bacteria. 



'» 



In order to "ive the organism the food constituents which are 

 presumably recjuired for its growth, an extract of some leguminous 

 plant is made, and this is used as a basis, in the same wa}^ that 

 meat extract forms the basis of media for the growth of bacteria 

 parasitic in animals. In this inAestigation the lupin was first 

 examined, and consequently this plant was employed. A kilogram 

 of chopped stems and leaves was boiled with a litre of Sydney 

 town water for several hours, and tlien pressed through a meat 

 press. The resulting extract was evaporated to less than a litre^ 

 filtered and made up to the volume. In the beginning of the 

 experiments a simple agar medium was prepared b}' adding '1 per 

 cent, agar to the infusion, and after the usual methods of procedure,. 

 10 cubic centimetres were caused to set in Petri dishes. Several 

 3'oung lupin plants were dug up, the nodules washed, cut oft', and 

 the outside sterilised bv steeping for 15 minutes in mercuric 

 chloride (1-1000), then for a minute in strong spii-it, followed by 



* iSchloesing and Laurent, Journal of the Chemiccal Society, Ixii. Abs. 

 II. 1021, and Ixiv. Abs. a. 13S, 336. 



t Winogradsky, Centialb. ftlr Bakt. 1 Abt. xvi. 129. 



