153 BOTANICAL GAZETTE [aucust 
Each species reproduces only within a certain range of factors. 
This range is probably a specific characteristic of each tree, possibly 
of each plant, and appears to be different even for trees growing 
together in the same association.?, Determination of this range 
for even a few of our more important trees would be a valuable 
contribution. 
New Yorx« Criry 
LITERATURE CITED 
1. BoerKER, R. H., Ecological investigations upon germination and early 
growth of forest trees. Univ. Neb. Studies 16:1-89. 1916. 
2. CovIL_e, F. V., Experiments in blueberry culture. U.S. Dept. Agric., Bur. 
Plant Ind. Bull. 193. 1910. 
3. Haw ey, R. C., and Hawes, A. F., Forestry i in | New England. New York: 
ened — Pt 
C. Hart, Laws of temperature control of the geographical dis- 
- tribution of tweed animals and plants. - Geog. Mag. 6:229-238. 
1894. 
5. SHALER, N. S., The geology of the island of Mount Desert, Maine. Report 
ee Secretary Interior 37987-1063. 1889. 
« Sureve, F., The vegetation of a desert mountain range as conditioned by 
climatic factors. Car. Inst. Wash. Publ. 217. rors. 
7 Truos, E., EOeN eh te all sent i maios Sta:; Saiu: Wis. Bull. 
249. 1975 : 
oem, R,, Balsam fir. US. Dept. Agric. Bull. 55+ 1914. 
_Stti (fond hat in pen eget in Ain he eis vg 
