lo Feb., 1910.] Tests zvith Cultures of Roai-tubercle Bacteria. 



beneficial results, and good results are also reported from the use of pure 

 cultures for lupins, peas, vetches and beans'. 



We may therefore conclude from European experiments that the 

 scientific use of suitable cultures on a limited scale, will be beneficial in 

 enabling legumes to grow in otherwise unsuitable soils', so' far. as European 

 conditions are concerned, and presumably also in a few sterile Victorian 

 soils. A point worthy of consideration is, ho'wever, as to how cultures 

 made in Europe stand transport to Victoria and how long vitality is re- 

 tained under the usual conditions of storage. 



Ordinary bacterium cultures at suitable temperatures' attain their 

 maximum development in a few days. After that they are on the down 

 grade, more and more dead forms being present in the culture, although 

 if kept cool living forms may still be present, in many cases for years, 

 in properly kept cultures without any renewals. No data appear to be 

 available as to the exact length of time a '' nitragin culture'' or " nitro- 

 culture " retains its eflEicacy To determine this, experiments were 

 necessary. 



Sufficient evidence of the difficulties which hedge about this question is 

 given by the results of Harding and Wilson (New York Experiment 

 Station, Bulletin No. 300, page 137), who have experimented on the in- 

 oculation of lucerne on 67 farms in ^t^ counties of the State. Only 

 one-third of these farms alread\ contained the root-tubercle bacterium of 

 lucerne in sufficient amount, and on the remaining two-thirds inoculation 

 of the seeds with bacterial cultures failed to give satisfactory results. 

 Complete success was, however, obtained by inoculating these fields with 

 soil from old lucerne fields at the rate of 150 lbs. to 300 lbs. per acre. 

 This is, of course, the natural method of inc<:ulation, since as the old 

 tubercles die the bacteria are set free and continue to live in the soil 

 for some time, reinfecting each new crop of the same kind. 



Some local investigation of the questions outlined above was evidently 

 necessary, and also tests were advisable of the bacterial cultures which 

 have been for some time on the market in Victoria, and have been ex- 

 tensively advertised by means of agents and printed circulars. The 

 cultures were obtained in the usual way by purchase, one being guaranteed 

 to contain bacteria for the inoculation of field peas, the other for the in- 

 oculation of alsike clover. The tests were carried out at the University 

 and at the Burnley Gardens. 



University Tests. 



The cultures were tested in the first instance bv using peas grown in 

 sterilized artificial nutrient solutions, three peas being giown. in each bottle. 

 No. I w'as inoculated, No. 2 was uninoculated, and No. 3 was inoculated, 

 but the nutrient solution contained no nitrates. The results are well 

 shown in the accompanying photogi-aph, the peas growing in the uninocu- 

 lated culture solution being distinctly taller than in the other two, while 

 in No. 3 (no nitrates) inoculation was quite unable to make good the 

 deficiency caused by the absence of nitrates. On examining the roots 

 of the plants grown in the culture solutions, it was seen that root 

 nodules were entirelv absent except from No. i. 



Before starting the experiments, the bottle and the nutrient solutions 

 were thoroughly sterilized, and the peas were also sterilized* while dry 

 by one minute's immersal in boiling water. Evidently, therefore, the 

 culture solutions did actually contain root-tubercle bacteria capable of 



* As regards root-tubernle bacteria. 

 D 2 



