312 BOTANICAL GAZETTE [OCTOBER 
amount of peroxidase occluded by clot, for after 24 hours of leach- 
ing the activity is just as great in the room-stored potatoes. 
TABLE V 
SHOWS INCREASE IN PEROXIDASE ACTIVITY IN COLD STORAGE POTATOES BY THE 
OHOL AND ETHER METHOD, BUT NO INCREASE WHEN THE TESTS 
ARE MADE WITH FRESH UNHEATED EXTRACT 
ee SECONDS REQUIRED FOR poe: ete To 
REACH STANDARD CO 
PoTaToO TUBER SAMPLE | Storage at 20°-25°C. | Storage at o° C. 
After 24 | After 24 
hours | hours 
Sis -trestnd anh. alcohol a said ( tee 60 20 28 20 
ether; heated to 70° C. in alco-;| 2...... 56 Hees 
ol for $0 MUAULES os ec in iss | yee 51 ee 
Ground with CaCO, and deter-({1....../ 35 Al loess 40 
minations made with fresh un- Boe eee 2 30 
Meabedettract. PElpsgo 3! ae as 
The following table is a summary of the metabolic changes 
thus far studied occurring in a typical lot of young potatoes stored 
at o° C. and 20-25°C. for a period of 6 weeks, tests being made 
every 2 weeks. Several lots were run, but as they all showed 
practically the same changes, only a typical table is given. 
TABLE VI 
SHOWS METABOLIC CHANGES OCCURRING IN POTATO TUBERS DURING AFTER-RIPEN 
G AT LOW TEMPERATURE 
or i | PEROXI- 
, — Guucosr | SucROsE | STARCH DrastTAasE | CATALASE DASE 
ee oe 
cc. ato 
pero to Seconds 
Days : digest ce. of Os pores oO 
ys *C. Percent {| Percent | Percent | roocc. evolved vie 4 
| starch a in 3 min, | standar 
| in 24 hrs color 
at 48° Ce 
oe \| 20-25 | 0.37 0.55 14.4 30 40.6 35 
oe r3 13.2 25 37.6 35 
Be \| 20-25 | 0.32 | 0.54 | -14 0) at 
(] o-+r 5 1.65 i ae 28.6 32 
Fe a eet tate 5 20-25 0.3 0.84 | 13.6 25 | 44. 32 
( 1 Bs5 28: fb  o8 | 20. 4. 26:4 25 
