142 



Journal of Agricultural Research 



Vol. XV, No. 3 



Appleman (i) seems to consider the plant material the main source of 

 destructive acids. In our work with seeds the hydrogen peroxids are 

 the main source of injurious acids. Without neutralization the two 

 more acid hydrogen peroxids mentioned above give (with Johnson 

 grass) only about one-third as much catalase activity as does the less 

 acid dioxogen. When all these peroxids are neutralized or an excess of 

 calcium carbonate is used, the three give more nearly equal catalase 

 activity. The more acid ones are still somewhat below the dioxogen, 

 due either to lov/er concentration or other inhibitors. Table II shows 

 the effect of the reaction of the dioxogen upon the catalase activity of 

 Johnson grass. 



Table II. — Catalase activity as modified by the reaction of the dioxogen 



[Johnson grass dry-stored i year. 70-mesh bolting cloth, o.i gm. of meal. 0.9 cc. of A7io sodium hydroxid 

 needed to neutralize 25 cc. of dioxogen to phenolphthalein] 



Table II shows that the natural acidity of dioxogen reduces greatly the 

 catalase activity of Johnson grass, but that an addition of sodium hy- 

 droxid from one-half of the amount needed for neutralization to phenol- 

 phthalein to twice the amount needed for such neutralization gives maxi- 

 mum activity. Dioxogen that is half neutralized to phenolphthalein is 

 still acid to neutral red. As is well known, neutral red turns practically 

 at the neutral point (H+= lo"'^), while phenolphthalein turns at a point 

 that is distinctly basic (H+ == iq-''). The filtrate from the dioxogen-cata- 

 lase mixture (the dioxogen being neutral to phenolphthalein) in the 

 above experiments is basic to neutral red, while the filtrate from the 

 emulsion of seed material is acid to neutral red. From all the facts here 

 reported it appears that catalase of Johnson grass is rather sensitive to 

 acids, but that it gives maximum activity in a considerable range of re- 

 action from very slightly acid to rather markedly basic. 



