210 PETRY: VEGETATION OF NEW YorK STATE 
species is held to indicate a direct causal relationship between the 
two. The writer is of the opinion that we have here a case in 
which the control of distribution of a plant association by the 
single factor of temperature is demonstrable; and that the plunge 
basin offers an exceptionally favorable opportunity to determine 
experimentally the mechanism of this control. Work is now in 
progress along this line. 
SUMMARY 
I. In the bottoms of certain plunge basins near Syracuse, 
New York, low temperatures prevail throughout the year. Data 
of air and soil temperatures are given for one such basin whose 
bottom lies at an altitude of six hundred ten feet above sea level; 
an area of some thousands of square yards in it remains throughout 
the year at a temperature below 70° Fahr. 
2. The bottom area of this basin is occupied by an association 
of plants characteristically Canadian in distribution. Analysis 
of the conditions in the basin demonstrates that temperature is 
the factor controlling their distribution in this area. 
SYRACUSE UNIVERSITY, 
YRACUSE, NEw YorK 
