1 66 



Journal of Agricultural Research 



Vol. XV, No. 3 



Supplementary experiments with peach embryos, with pyrocatechol 

 and para-cresol as oxidase reagents, showed practically no oxidase activ- 

 ity either with dry-stored embryos or with after-ripened embryos. In 

 this connection the color reaction in the oxidase reagents is of interest. 

 The pyrocatechol and pyrogallol solutions became very slightly colored 

 during the experiments. This coloring was barely perceptible with the 

 material which had not after-ripened and sHghtly more intense with 

 after-ripened material. With para-cresol as the reagent and in control 

 lots with no reagent there was no change in color. 



OXIDASE ACTIVITY AS RELATED TO GERMINATION 



Johnson grass seeds collected on September 9, 191 6, were incubated 

 at 20° C. for several days late in November, 191 7, and then with the 

 temperature alternation 25° to 40° until nearly all had germinated. 

 Seeds which showed no sign of germination were then picked out, 

 ground, and tested for oxidase activity in comparison with dry seeds 

 and with seeds which had germinated, and in comparison also with the 

 sprouts produced by another sample of the same original lot which had 

 been germinated at 20° after first heating for i hour at 81° and steriUzing 

 with 5 per cent silver nitrate.^ 



Many of the seeds in the last-mentioned sample had reached an ad- 

 vanced stage in germination, some coleoptiles being over 10 cm. long. 

 The elongated coleoptiles and a few of the roots were broken off, crushed, 

 dried before a fan, and ground for oxidase determinations. 



The germinated seeds which had been ground entire were in various 

 stages of growth. The longest coleoptile was 8 cm. long and the longest 

 root 4 cm., but a large majority were less than one-half as long as these. 

 Before being ground these germinated seeds had been crushed and dried 

 before a fan. Table XXX gives the results of these experiments. 



Table XXX. — Relation of oxidase activity to germination 



Material and condition. 



Johnson grass 8604 (collected on Sept. 9 

 1916): 



Ground dry 



Incubated several days at 20° C. 

 then at 25° to 40° C. — 



Not germinated 



Germinated 



Sprouts . . . .*. 



Reduction of pressure. 



20.5 mm. in 7^^ hours. 



16.5 mm. in 7^ hoius. 

 16.0 mm. in 7>^ hours. 

 14.0 mm. in 7>^ hours. 



1 Although the sterilized seeds were very thoroughly washed, first with distilled water, then with sodium 

 chlorid solution, and finally with distilled water, oxidase activity in the ground seeds was almost com- 

 pletely inhibited, probably by adsorbed silver. Of course the sprouts weref ree from this inhibiting agent. 



