von Schrenk — Trees of St. Louis as Influenced by Tornado. 31 



chanf^es in the wood. It is very unreliable, as Kny has 

 shown, to judge of the age of a twig by its external markings, 

 i. e., leaf and bud scale scars, branching, etc., and in deter- 

 mining the age only a personal knowledge of the twig is to be 

 considered. The confusion prevailing on the day after the 

 storm prevented the drawing of many twigs, hence the re- 

 sults are not as full as might be desired. Examinations of 

 numerous twigs this spring (1897) showed appearances similar 

 to those in the twig figured and may be considered as con- 

 firmatory in many respects. 



Sections were made of the twig described, and these are 

 shown diagrammatically in fig. 1, the dotted lines indicating 

 the point at which the section was made. It was very evi- 

 dent that two rings had been formed during the year 1896. 

 The diagrams of the sections need no explanation. A closer 

 examination of the wood of that year was made. The spring 

 wood of the sycamore consists of very large angular vessels 

 with few wood elements. The latter increase in number 

 toward the fall wood, and at the end of the season's growth are 

 much flattened radially (PI. V. fig. 1). The wood formed be- 

 fore the storm was normal spring wood. This rather abruptly 

 passed over into wood (PL V. fig. 2, b) looking much like 

 normal fall wood. When the twig began its second growth 

 in June a second spring wood appeared (PI. V. fig. 2, a) 

 which was very distinctly separable from the wood found 

 a month before, thus presenting in all respects the appearance 

 ordinarily seen in normal wood. In fact, the two figures 

 (PI. V.) are almost identical. On PI. III. the upper figure 

 represents the cross-section of a sycamore twig taken from ao 

 uninjured tree. The inner ring is that formed in 1895, the 

 next one in 1896, the lower figure is from a section of the 

 twig already described. The inner ring is that for 1895 ; the 

 narrow one following was formed before the storm in 1896; 

 the wood beyond, after the storm. PI. IV. shows similar 

 conditions existing in a twig of a soft maple. In the latter 

 the double ring was in all respects similar to that found in 

 the sycamore. 



The various twigs were studied with a view to determine 

 how far back the abnormal ring could be traced. In the 



