450 BOTANICAL GAZETTE [JUNE 
Two general types of roots could be separated, according to the 
presence or absence of mycorhizal fungi. Most ericads have 
mycorhiza, but none were found upon the roots of Andromeda or 
Chamaedaphne. In working over the material furnished him by 
the author, McDoucatt found that Andromeda occasionally gave 
evidences of mycorhizal appearance, although further investigation 
failed to reveal its presence. Mycorhiza was found on Larix lart- 
cina, Acer rubrum, and Vaccinium macrocar pon, but was not noticed 
on any of the following plants: Carex filiformis, Sagittaria latifolia, 
Eupatorium perfoliatum, Dulichium arundinaceum, Asclepias in- 
carnata, and Aspidium thelypteris. 
The absence of mycorhiza on Chamaedaphne and these other 
plants demonstrates that it is not a necessary adaptation to the bog 
environment. The presence of resin deposits (TRANSEAU 49) is 
often a noteworthy feature of the roots of bog plants. Root hairs 
were not observed, although TRANSEAU (49) found that in culture 
solutions, which were well aerated, normal roots with root hairs 
were produced in Larix. 
During the summer, the roots of the bog plants, at least appar- 
ently, have an abundant water supply, although as a matter of fact 
the Sphagnum which surrounds the roots may be physiologically 
dry, even when apparently wet, on account of its great ability to 
soak up and retain water (Fri and ScHROTER 18, and Davis 14). 
In general, however, there is standing water beyond the ability of 
the Sphagnum to absorb, and therefore the bog plants have a supply 
to draw on throughout a normal season. Seasons of drought, 
therefore, would be the critical ones, and that of 1911 was a case 
in hand. In so far as could be observed, it did not appear that the 
ericads were suffering from lack of water even on the hottest and 
driest days. The leathery nature of their leaves makes it nearly 
impossible to tell whether the plants are wilting or not, even when 
herbaceous vegetation was obviously wilted. In the natural dis- 
tribution of these plants, droughts are not sufficiently extreme 
nor of sufficient duration to dry out the Sphagnum. The great 
ability of Sphagnum to soak up and retain water localizes the 
water within reach at the expense of the surrounding area. During 
the summer this often results in the elevation of the water table 
