THE PERIODICITY AND DISTRIBUTION OF RADIAL 
GROWTH IN TREES AND THEIR RELATION TO 
THE DEVELOPMENT OF “ANNUAL” RINGS. 
J. G. Grossenbacher, 
INTRODUCTION. 
The study of the so-called ‘ 4 animal” rings in trees has re¬ 
ceived the attention of numerous investigators during past years 
and still claims the interest of many. Research along that line, 
however, is not as active as formerly apparently owing to the 
general prevalence of the idea that the causes of ring formation 
are beyond our ability to fathom at present; although it is gen¬ 
erally conceded that an environment resulting in discontinuous 
radial growth is somehow responsible for their occurrence. 
In studying crown-rot of fruit trees 1 I found that radial 
growth and especially its distribution on trees during late sum¬ 
mer seemed to have a relation to the occurrence of the disease. 
A number of more or less incidental remarks had been noted in 
the literature concerning irregularities in the time of commence¬ 
ment and closing of cambial activity, but the irregularities oc¬ 
curring in fruit trees during late summer and fall were found 
so marked that the literature was more carefully examined. The 
number of significant papers on the subject proved so large and 
the conclusions drawn so varied and contradictory that it seemed 
desirable to discuss radial growth and the factors thought to 
determine its distribution in a separate paper before writing up 
1 Crown-rot, Arsenical poisoning and winter-injury. N. Y. State Agrl. 
Expt. Sta. Tech. Bui. 12:367-411. 1909. 
Crown-rot of fruit trees: field studies. N. Y. State Agrl. Expt. Sta. 
Tecli. Bui. 23: 1-59. 1912. 
1— -S. A. 
