SEED STERILIZATION AND ITS EFFECT UPON INOCULATION. 



9 



certainly could not withstand such quantities of toxic substances in 

 solution as have proved fatal in these experiments to the more 

 resistant Bacillus suhfJUfi. 



ACTION OF HYDROGEN PEROXID. 



Small lots of peas, beans, and alfalfa seed in flasks or test tubes 

 were treated for thirty minutes with full-strength commercial hydro- 

 gen peroxid (3 per cent), rinsed three times with sterile distilled 

 water, and then inoculated with tested specific cultures of Pseudo- 

 monas radicicola. A duplicate series was Avashed with sterile water 

 several times before inoculation; platings made from such washed 

 seeds showed them to be nearly sterile, no bacteria and only a few 

 molds developing. One lot of each kind of seed was dried by rolling 

 in sterilized soil, the soil then being dusted from the seed ; one lot 

 was dried by contact with sterile filter paper; and one lot was placed 

 in a desiccator, all seed being kept in sterile petri dishes. Platings 

 were made by shaking ten seeds thoroughly with 10 cubic centimeters 

 of sterile water, and plates were then poured with the nitrogen-poor 

 synthetic agar (cane sugar, 10 grams; potassium phosphate, 1 gram; 

 magnesium sulphate, 0.2 gram ; agar, 15 grams ; and tap water, 1,000 

 cubic centimeters) ordinarily used for growing Pseiidomonas radici- 

 cola. The results were as shown in Tables VI and VTI : 



Table VI. — Bacteria alive mi culture-treated {sterilized) .^ecd. 



Table VII. — Bacteria alive on culture-treated seed, previoush/ intshcd with 



sterile water. 



Bean seed. 



Time when plat- 

 ings were 

 made. 



Dried in — 



Soil. 



Immediately af- No. 

 ter treatment ..: 550 



1 day after treat- I 

 ment I 450 



2 days after treat- I 



ment 450 



5 da vs after treat- 

 ment I .500 



[Cir. 67J 



Filter I ^P^" 

 dish. 



paper. 



No. 

 1,500 



450 



325 



No. 

 1,800 



1,350 



750 



225 1,000 



Desic- 

 cator. 



No. 

 2,000 



1,800 



900 



Mold. 



Pea seed. 



Soil, 



No. 

 2 



5 



2 

 



Dried in — 



™te^lKi 

 P^P^'- §fsh 



No. 

 60 















No. 

 200 



275 



300 



180 



Desic- 

 cator. 



No. 

 1,100 



300 



180 



Mold. 



i^oW. 



No. 

 5 



3 











Alfalfa seed. 



Dried in — 



Filter 

 paper. 



No. 



Open 



petri 

 dish. 



No. 

 660 



400 



550 



100 



Desic- 

 cator. 



No. 

 450 



500 



400 



200 



