AGRICULTURAL BOTANY. 629 



absolute alcohol. The precipitate obtained was washed in alcohol and ether, 

 filtered off and dried, and the enzymatic powder thus produced allowed to act 

 on wheat protein, the nitrogen content of which was about 16 per cent. In 

 each experiment 3 flasks were used, each containing the same quantity of 

 iirotein, enzymatic preparation, and water. To one flask tannic acid and a 

 trace of sodium acetate were added at once; the other flasks were allowed to 

 stand for 24 hours at a temperature of 50° C, when they also received the 

 same quantity of tannic acid and sodium acetate. The tannic acid precipi- 

 tates the insoluble protein and the quantity of nitrogen remaining in the filtrate 

 was assumed to represent the proteolytic activity of each enzym. 



A direct test was made of some 12 species of the fleshy fungi, using the juice 

 pressed from fresh plants and allowing it to act on the wheat protein for 4 

 hours at 50° C. Cultures of several of the lower fungi and bacteria were also 

 made and tested for proteolytic activity. Proteolytic action was demonstrated 

 for the species of fungi and bacteria examined. 



The g'ermicidal action of metals, A. C. Rankin (Proc. Roy. Soc. [London], 

 Ser. B, 82 (1910), No. B 553, pp. 78-87, fig. /).— The results of experiments 

 with plates of pure zinc, aluminum, and copper immersed in water are given. 

 The ])urpose was to investigate the real cause of the germicidal etleets of these 

 metals, whether it is due, as heretofore claimed, to the formation of hydrogen 

 I)eroxid and its subsequent action on the bacteria or to some other factor not 

 yet discovered. In all the experiments the plates of metal were allowed to 

 act for one hour on Montreal tap water to which Bacillus coli had been added, 

 and the results tested by counting the number of colonies obtained by inoculat- 

 ing sterilized agar plates with a drop of this water and then incubating the 

 plates for 24 hours at a temperature of 37° C. 



Hydrogen peroxid was formed in the presence of zinc and aluminum, but 

 not in the iiresence of copper. The germicidal action took place only while the 

 metal plates were in the water; if the plates were removed and the water in 

 which they had been immersed was allowed to stand for 12 hours and then 

 tested, it showed no appreciable effect on bacteria, except slightly in the case 

 of copper. The amount of hydrogen peroxid developed in 1 hour with zinc and 

 aluminum was so small that it produced no perceptible effect on the colon 

 bacilli. The germicidal action occurred with copper as well as with the other 

 two metals, although it formed no hydrogen peroxid in the water. The metal 

 plates produced no germicidal action when immersed in oxygen-free water. 



The authfir concludes that the germicidal power of these metals is not due 

 to the hydrogen peroxid formed or to the minute quantity of the metal that 

 may be dissolved in the water, but is caused by the metals dissociating the 

 oxygen molecule. The free ions thus liberated oxidize the bacteria and thus 

 destroy them. 



The effect of mineral salts on the respiration of germinating seeds, W. 

 Zaleski and A. Reinhard (Biochcm. Ztschr., 23 {1909), Xo. 3-J,, pp. 193-214, 

 (Jgms. 16). — Experiments were made with lupine, maize, and pea seedlings in 

 solutions containing various chemicals and the effect of the single salts and 

 their combinations upon the respiration of the plants was determined. 



Of the salts potassium nitrate, potassium phosphate, sodium nitrate, sodium 

 phosphate, and magnesium sulphate when iso-osmotic with 0.1 per cent solu- 

 tion of potassium nitrate increased the energy of respiration beyond the maxi- 

 mum observed by Krzemieniewski (E. S. R., 14. p. 943), who claimed that 

 only potash and nitric salts were able to stimulate respiration to any appre- 

 ciable extent. The nutrient effect of the salts was not found to be equal to 

 that described by many others. Zinc sulphate stimulated respiration, but it 



