[HARBISON & BARLOW] NODULE ORGANISM OF THE LEGUMINOSAE 183 



is wrapped in a sheet of directions for using and packed with cotton 

 in a wooden mailing case. 



The materials required for 1,000 packages of nitro-culture are as 

 follows : — 



Agar, 3,500 grams $ 4 00 



Maltose, 3,500 grams 10 00 



Bottles, 1,000 at 2 cts. apiece 20 00 



Printed labels and directions, 1,000 3 00 



Mailing cases, at 4 cts. each, 1,000 40 00 



Postage stamps at 7 cts. per case, 1,000 70 00 



$147 00 



$147.00 for 1,000 bottles, or about 14f cts. apiece, as each bottle 

 contains enough culture for 60 pounds of seed, the actual cost per acre 

 will be less than 4 cts. Making allowance for labour, steam, etc., 

 these cultures should not cost more than 25 cents per acre, as compared 

 with $2.00 per acre charged by some commercial firms. 



This method of preparing and using nitro-cultures offers several 

 advantages. Each culture is, or may easily be, a pure culture and 

 a living culture, for the growth in the agar is easily seen and is 

 highly characteristic, so that failure to grow, or possible contaminations, 

 are easily detected. There are at least two staining reactions, both 

 easy of application, and so far as known, peculiar to Pseudominas radi- 

 cicola (see staining methods). The burden and responsibility of pre- 

 paring the media and growing the cultures is placed, not on the shoul- 

 ders of the farmer, but rests with the bacteriologist, where it belongs. 

 A competent worker can by these means isolate a pure culture of the 

 nodule bacteria from a leguminous plant, grow it, prove that it is 

 appropriate and efficient and distribute it alive and in pure culture at 

 reasonable cost, and an intelligent farmer can apply the culture to his 

 seed and observe whether or not the nodules form and whether or not 

 the crop is benefited. 



12. A number of cultures prepared in this manner were distributed 

 throughout Canada in the spring of 1905. The results of this distri- 

 bution were published in March, 1906, by the Ontario Department of 

 Agriculture as Bulletin 148 — '' Co-operative Experiment with Nodule- 

 forming Bacteria," and a short summary of these results are here 

 given. 



