igig] 



ROSE— AFTER-RIPENING AND GERMINATION 



293 



seeds have a great power of increasing their alkali absorption, which 

 may be due to lipase activity. 



Catalase.— Determinations of catalase activity of dry, after- 

 ripened, and germinating seeds were made by means of Appleman's 

 apparatus (i). The samples, ground in a mortar, were all reduced 

 to the same degree of fineness by rubbing them through bolting 

 cloth. The catalase determinations were made at 25° C. To 5 cc. 

 of water containing o . 02 gm. of pulverized seed material was 

 added 5 cc. of Oakland dioxygen and the amount of oxygen released 

 was measured after i, 2, 3, and 5 minutes of activity. Appleman 

 has pointed out that small amounts of acid greatly reduce or entirely 

 destroy catalase activity. In order to remove this possible source 

 of error the Oakland dioxygen used was neutrahzed by the addition 

 of N/io NaOH, or an excess of CaCOj was added to the meal. The 

 data given in table VII are the averages of duphcate determinations. 

 They show that dry, after-ripened, and germinating seeds, in the 

 order named, exhibit increasing catalase activity. Eckerson (8), 

 employing microchemical methods, arrived at similar conclusions 

 for seeds of Crataegus. 



TABLE VII 



Condition of seeds 



1. Dry seeds 



2. After-ripened (dried 2 daj-s) . 



3. After- ripened (dried 2 days) . 



4. After-ripened (not dried) .... 



5. Germinating 



Re.action of 



REAGENT 



Oxygen in cc. liberated after 



Neutralized* 

 Neutralized* 

 With CaCOj 

 With CaCOj 

 With CaCO, 



I minute 



2.5 

 7-1 

 6.8 



6.75 

 19.4 



2 minutes 3 minutes 



4.2 



11. 8 



11. 9 



II-3 

 27.86 



5-25 

 15-4 

 14.8 

 15 OS 

 315 



S minutes 



7.0 



21.5 

 21 .05 



20.75 

 37-03 



'0.80 CC. N/io NaOH to neutralize 25 cc. dioxygen. 



Drying after-ripened seeds for 2 days at room temperature has 

 no effect on the amount of oxygen hberated, as is shown by com- 

 parison of samples 3 and 4. 



Further evidence for the effect of the acid of the dioxygen upon 

 catalase activity is shown in table VIII. Determinations made 

 with after-ripened seeds not dried and with germinating seeds gave 

 similar results. A comparison of the last 2 determinations show 



