30 



Trans. Acad. Sci. of St. Louis. 



a number of years; in one instance a branch fifteen years old 

 had no less than ten double rings. An icemantle is formed 

 between the bark and new wood, crushing the latter. When 

 this thaws it remains in its crushed condition and a break is 

 thus formed which is partially filled by the expanding cells of 

 the medullary rays, and by parenchymatous cells, developed 

 from the cambium. Ultimately normal tracheids are formed. 

 In the course of time the masses of wood are separated by a 



fine brown line. It will be 

 noted that this manner of 

 separating wood rings has 

 nothing in common with that 

 seen in normal wood, where 

 there is a distinct formation 

 of different kinds of cells in 

 the fall and the spring. 



On examining the trees in 

 the storm district on May 28, 

 very few trees were found 

 which had twigs of that year, 

 for in the majority of trees, 

 these twigs had been torn 

 away. Thus it came that the 

 observations had to be re- 

 stricted to the silver maples 

 and sycamores. Fig. 1 is 

 Fig. l. from a sketch of a sycamore 



twig made after the storm, to which has been added a sketch 

 of the same twig in the spring of 1897. At o is the growth 

 of 1895. It had two lateral buds which developed in April, 

 1896, into two branches. The storm tore these away leaving 

 but the lowest part of each, with one axillary bud. In June 

 these buds grew out into short branches (b) which bore 

 normal buds in the fall. At c and c' are seen the broken 

 ends of the branches. In April, 1897, the buds of the 

 previous fall grew normally, and in May a short branch 

 was at each axil. A cessation of growth had then existed 

 for about a month from May to June, 1896, and it re- 

 mained to be seen whether this had caused any marked 



