CHANGES ACCOMPANYING BREAKING OF REST PERIOD 17 



was greatest during the first day after which it became less notice- 

 able. 



The respiration of oak twigs was affected less by etherization 

 than that of either apple or mulberry. The stimulation seemed to 

 increase from the first to the third day. Etherized ash twigs did not 

 give off very much more CO 2 than untreated twigs. 



In all cases etherized and untreated twigs were placed in the 

 greenhouse in beakers of water where they were allowed to grow. 

 The treated apple buds came out more than a week earlier than the 

 untreated; in case of the mulberry, the etherized buds came out 

 several days before the untreated, but they soon stopped growing, 

 allowing the untreated buds to overtake them. The etherized and 

 untreated oak and ash buds opened about the same time. Treat- 

 ment apparently had no effect. 



It was noticeable that the species in which CO 2 production was 

 stimulated most by etherization, opened their buds before the un- 

 treated. When the stimulation continued to increase for several 

 days, there was no reaction in the development of the young growth; 

 but when the stimulation declined very quickly a reaction did occur. 

 When respiration was stimulated but very little, the treatment had 

 little effect in causing the buds to open earlier. 



EXPERIMENT 3. CO 2 PRODUCED BY ETHERIZED AND BY 

 UNTREATED APPLE TWIGS AT DIFFERENT TIMES 

 DURING THE SEASON 



The material for this series of experiments was secured from a 

 number of thrifty fifteen-year-old Jonathan apple trees of similar 

 vigor, which were growing in the Agricultural Experiment Station 

 orchard at Columbia, Missouri. The twigs were collected and 

 divided into lots as previously described. The lots contained about 

 40 twigs each and weighed about 150 grams. 



The preliminary treatment with ether was carried out in the 

 same way as described in the previous experiment. Immediately 

 after the preliminary treatment, the material was put in the respira- 

 tion chambers and CO 2 determinations begun at once. 



The dates on which the material was collected, as well as the 

 results of the CO 2 determinations, are given in Table 5. Calcula- 

 tions were based on the fresh weight of the twigs. In all cases the 

 figures are averages of three samples which represented over 400 gr. 

 of material. The KOH bulbs were weighed once every twenty- four 

 hours. 



