Development of the Vegetation of New York State 65 
—e. g. Machias— or in the Adirondacks. The question 
arises as to whether the factor of temperature plays a role 
in the occurrence of boreal species in these bogs or whether it 
is not a matter of the physical and particularly of the chem- 
ical nature of the substratum. In this bulletin I am discuss- 
ing bogs in connection with vegetation development as deter- 
mined by the substratum, page 119, but I am disinclined 
to regard the factor of temperature as of no special moment. 
Certainly it is a common experience that bog waters are cold. 
My own experience in using Sphagnum in starting seeds 
to germinate, ete., leads to the conviction that rapid evapora- 
tion from wet Sphagnum operated to lower the temperature 
materially. The absorption and giving off of heat by bog 
water must be retarded not only by ‘the covering of bos 
vegetation but by the effect of the peaty substratum in cheek- 
ing free movements of the water. 
Nevertheless Dachnowski* found that in a Cranberry bog 
the temperature of the peat substratum during the spring and 
summer is not lower than that of other soils and is more 
uniform than that of air. 
On the other hand, investigations with respect to conditions 
under which frosts occur in cranberry bogs appear to sup- 
port the lower temperature claim. Thus Wilson ? discussing 
the effect of soil and soil covering on frost says: ‘“ The 
writer found that old cranberry bogs covered with a thick 
carpet of vines were much more liable to frosts than were 
bogs recently planted. It was believed that the thick cover- 
ing of vines prevented a large part of the heat received from 
the sun during the daytime from reaching the soil and since 
but little heat was stored up by day, only feeble resistance 
was offered to the fall of temperature at night.” 
“In the Cape Cod cranberry marshes it is the practice to 
spread about half an inch of sand over the surface of the 
marshes each year, thus covering the dry vines and furnish- 
Eiachnowski, Alfred, The vegetation of Cranberry Island (Ohio) 
and its relation to the ‘substratum, temperature and evaporation. Bot. 
Gaz., 52):1911- 
2 Frosts in New York; loc. cit., p. 516. 
