CHANGES ACCOMPANYING BREAKING OF REST PERIOD 29 



The influence of the intensity of a treatment on the enzyme 

 activity of the twigs is shown in Table 9. The data indicate that 

 in most cases a weak dose increases the fermentative action while 

 a stronger dose has no influence or even causes a diminished activity. 

 Unfortunately, most of these experiments were carried out late in the 

 season. 



It is very probable that during the early part of the season 

 a strong dose might have increased the enzyme work when a weaker 

 dose would have had no effect. This table shows very nicely how 

 different varieties of apples behave in respect to their enzyme 

 activity under similar treatment. 



Another factor which influences enzyme activity is the intervals 

 after treatment as shown in Table 10. In most cases the treated 

 material showed a greater activity after an interval than it did 

 immediately after treatment. (Cf. 1, 2, 3, 4, 5, 8, Table 10.) In 

 some cases an interval may bring about less enzyme activity than 

 immediately after treatment, even tho the ferments are still more 

 active than those in untreated twigs. The interval seems to be 

 unfavorable for the enzyme activity of the untreated material. 

 (Cf. 1, 3, 4, 5, 6, Table 10.) In a few cases a rather long interval 

 seemed to bring about an increase in the fermentative activity, tho 

 an excessively long interval again diminished the rapidity of the 

 enzyme action of untreated material. (Cf. 7 and 8, Table 10.) 



Table 11 is inserted in order to show how the enzyme activity 

 of different tissues of Pyrus Mains, Linn, vary with and without 

 treatment. "Cortex," as previously explained, refers to all soft 

 parts of the twig including lateral and terminal buds. "Twigs 

 minus cortex" is what remains after removing the soft parts. 

 The other terms used in the table are self-explanatory. 



As might be expected the different tissues vary as far as their 

 enzyme activity is concerned. The older cortex was least active at 

 the latter part of the season. (Cf. 1, Table 11.) The same tissues 

 were tested for their enzyme activity during October. Unfortunate- 

 ly at that time the plan of recording the enzyme activity had not 

 yet been adopted and therefore the results are not included in the 

 table. The observations noted were as follows: "Untreated material 

 showed a little more action than etherized; bud material showed 

 least; 1 year cortex medium; older cortex most enzyme activity." 

 This is the reverse of what was obtained in the late season. 



The reasons for choosing the cortex for most of the enzyme 

 determinations have been mentioned. Table 11 gives experimental 

 evidence which indicates that the one-year cortex is somewhat more 



