New York Ageicultueal Experiment Station. 283 



The following table shows the changes in circumference induced by 

 changes in temperature: 



Table I. — Changes in Circumference op Apple Tree Trunks During Winter. 



As may be seen in the last vertical column of this table the per- 

 centages of decrease in the circumferences of the 8 tree trunks varies 

 from 1.8 to 3.1, and the average is a little over 2 per ct. It is 

 also interesting to note that the contraction resulting from a change 

 of temperature from 6.6° C. to — 9.4° C. is not as great per degree of 

 change in temperature as it is in the range from — 9.4° C. to — 28.3° C. 

 In the first case a change of 16° C. resulted in an average con- 

 traction of only a little over 3 mm. or 0.19 mm. per degree of change; 

 while in the second an additional change of 18.9° C. caused a con- 

 traction averaging 8.8 mm. or 0.46 mm. per degree of change. The 

 measurements taken on April 6, although made at a higher temper- 

 ature than those of November 8, averaged less; and none of them were 

 above the first November measurements. Possibly that is an error 

 of observation, yet it may indicate a slight diminution in size due 

 to a loss of water during winter. 



Tree trunks cleft open during the first excessive cold period. — The 

 excessive cold period in the winter of 1911-12 came during the first 

 week of January with a minimum temperature of — 31.1° C. On 

 January 6 quite a number of tree trunks in the above apple orchard 

 were cleft open a little above the ground and others in the lowest 

 crotches. The clefts in the trunks were from 2 to 5 dm. long and 

 from 5 to 15 mm. wide. They extended at least to the pith as shown 

 by the insertion of a sharpened stick. The clefts were mostly on 

 the north and west sides. The crotch clefts were always at right 

 angles to the branching and usually widest above, appearing as 

 though the crotches had been split by driving in a thin wedge from 



