38 Trans. Acad. Sci. of St. Louis. 



always show a marked rise in temperature above that of 

 the atmosphere. Thus the highest is met with in dead trees. 

 In live trees, unless there is a flow of water in the new wood, 

 there is a tendency to equalize the differences in temperature 

 caused by excessive insolation. 



In the trees of the storm district the stoppage of this flow 

 of water was felt very soon. During the summer of 1896 

 the roots continued to send water into the new wood, and the 

 new leaves kept up a feeble current. In the spring of 1897, 

 however, this current was probably very small, for by this 

 time the roots no longer absorbed very much water. The 

 months of June, July, August and September had some un- 

 usually hot weather. In June, from the 11th to the 19th, the 

 temperature rose daily above 91° F. (to 96° F. on the 17th); 

 again, from June 29th to July 10th, the same was true. In 

 August, for four days it was 98° F, and from August 26 

 (101° F) to September 16th, almost three weeks, the average 

 maximum temperature was 95° F. These are temperatures 

 as recorded at the St. Louis Weather Bureau, and in unshaded 

 places, such as Lafayette Park, they were probably some 

 degrees higher. Judging from previous observations, the 

 temperature between wood and bark in the trees of Lafayette 

 Park must have risen to a height sufficient to destroy the 

 delicate cambium cells. With such a small water supply, 

 rapid drying took place, and the bark, breaking away from 

 the woody cylinder, finally peeled off in large pieces. This, 

 as has been said, was true particularly of the maples, which 

 had a smooth bark. Those trees whose trunks had been 

 wrapped with cloth, suffered as much as the unwrapped ones, 

 in many cases more so. The bark peeling took place mainly 

 on the south and southeast sides, though cases of scorching on 

 western exposures were met with. The bark broke away from 

 the branches as well as the trunk, and by the end of September, 

 there was many a tree left standing with no bark whatever 

 on the southwestern side. Under the powerful insolation, 

 rapid drying of the wood occurred, causing longitudinal split- 

 ting, which bore much resemblance to frost cracks. PI. 

 VIII., fig. 3, shows a tree where the wood on the southern 

 side has split in this manner, while the northern section was 



