Oct. 21, 1918 



Catalase and Oxidase Content of Seeds 



145 



Table V shows the diameter of the cells of various parts of the two 

 seeds mentioned in Table IV; also the pore diameter of some of the 

 sieves used. Maximum activity is obtained when the average diameter 

 of the sieve mesh is several times the diameter of the cells. The greater 

 injury from fine pulverizing in Johnson grass may be due in part to the 

 larger average cell diameter. Johnson grass catalase may also be relatively 

 sensitive to mechanical agitation, as later sections show it to be to heat 

 and aging effects. The endosperm of grasses has extremely low cata- 

 lase activity, so it is left out of consideration in this connection. It is 

 evident from the facts mentioned in this section that attention must 

 be given to uniformity and fineness of pulverization. 



Table V. — Diameter of cells of various parts of seeds of Johnson grass and crimson 



clover 



Material. 



Crimson clover: 



Cells of cotyledons 



Hypocotyl, except small cells of plerome 



Johnson grass: 



Scutellum, except elongated enzym layer 



Coleoptile and coleorhiza same, except small primordial cells 



200-mesh bolting cloth 



loo-mesh bolting cloth 



70-mesh bolting cloth 



Sieve with o.6io-mm. holes 



Cell or 

 mesh di- 

 ameter. 



16- 40 



15- 30 



33- 66 



16- 33 

 33- 75 



140-183 



2 14-2 50 



610 



DEGENERATION OF THE POWDER 



The powder ready for catalase determination degenerates rather rap- 

 idly when stored in a desiccator over quicklime. Table VI shows typical 

 data for Johnson grass, the only species tested. This degeneration may 

 be due in part to excessive drying, but it is probably in the main an 

 aging change. A later section shows that there is a slow time degener- 

 ation in intact seeds. The morphological integrity, however, seems to 

 secure very slow degeneration. From the results reported in this sec- 

 tion it is evident that it is best to grind and screen the seed material 

 just previous to making the catalase determinations. 



Table VI. — Degeneration of catalase in the powder of Johnson grass seeds 



Period of storage of powder. 



I day. .. 

 54 days. 



