Dec., 1909.] 
Evaporation in a Bog Habitat. 
2 3 
An inspection of this table shows that rainfall has had the 
most marked effect upon the evaporation rate in the Maple- 
Alder zone, but it is very evident also that this was not the only 
factor. The influence of temperature in either station is not so 
apparent for so limited a number of readings. It is quite prob- 
able that the missing data for wind velocity would account for 
some of the results which do not seem to agree with the data at 
hand. 
The effect of the growth of the leaves in the early part of the 
season, and their fall at the end of the period of observation is 
quite apparent in the readings of the Maple-Alder zone. The 
readings of the first and last two weeks in this zone are relatively 
high. If we consider the time from May to August as the critical 
period for growth and reproduction in plants, then the greatest 
evaporation observed is that of May 21 in the Maple-Alder zone, 
while the greatest loss in the Central zone occurred during the 
week ending July 24. However, the bearing of these data to 
plant growth in bogs will be discussed elsewhere. 
To Prof. A. Dachnowski, under whose direction this work 
was planned and carried out, I wish to express here, my sincere 
appreciation for many helpful suggestions. I also wish to 
acknowledge the aid of a grant from the McMillin Research 
Fund, to cover the expenses of the field work. 
LITERATURE. 
1. Dachnowski, A., The Toxic Property of Bog Water and Bog Soil. 
Bot. Gazette 46 : 130. 1908. 
2. Bog Toxins and Their Effect Upon Soils. Bot. Gazette 
47 : 389. 1909. 
3. Livingston, B. E., Evaporation and Plant Development. Plant 
World 10 : 269. 1907. 
4. , Evaporation and Plant Habitats. Plant World 11:1. 
1908. 
5. — , Evaporation and Centers of Plant Distribution. Plant 
World 11: 106. 1908. 
6. Shaw, C. H., Vegetation and Altitude. Plant World 13 : 63. 1909. 
7. Transeau, E. N., The Relation of Plant Societies to Evaporation. 
Bot. Gazette 45 : 217. 1908. 
8. The Monthly Weather Review 35 : 114, 311. 1907. 
9. Forest Influences. Bull. No. 7 : 39. Forestry Div., U. S. Dept. Ag. 
10. Marvin, C. F., Methods and Apparatus for the Observation and Study 
of Evaporation. Monthly Weather Review 37 : 141, 182. 1909. 
