1921] EMERSON—BOG PLANTS 371 
deviation from this direction being chiefly from the interference 
of the diagonal glass side of the growing box. It is also noteworthy 
that in both of these cases laterals were lacking. In garden soil 
in which a water table was kept, capillarity caused the water to rise 
until the soil was practically saturated to the surface. Only one 
pine seedling lived throughout this part of the experiment. A 
number of seedlings started to grow, however, and all behaved in 
the same way. All the tap roots showed a slight tendency to pene- 
trate the soil, but the plants soon fell over and the roots grew in an 
approximately horizontal direction, producing no laterals (fig. 9 C). 
Those growing in peat in which a water level was kept behaved in a 
still different manner. On account of the fibrous spongy structure 
of the peat, aeration was possible to the water surface. The tap 
roots grew downward about as in the moist garden soil and peat, 
although somewhat less rapidly. The most obvious difference 
began to appear when the tips of the tap roots reached the water 
level, when growth almost completely ceased. In a few cases the 
roots continued to grow slowly for some time after reaching the 
water level, but in all cases these longer roots died back to about 
the surface of the water. Strong laterals always appeared and 
took approximately the horizontal position. The study of this 
species was suggested by the statement made by PuLtinc (7) that 
Pinus Strobus has ‘‘a deep rigid root habit.”’ In examining the 
root systems of this tree at various ages in the Hillside bog and at 
Mineral Spring no root was found extending more than a few 
centimeters deep and all were horizontal. From this experiment 
and from field observation it is obvious that the tap root is 
ephemeral under bog conditions, and that very shallow horizontal 
laterals make up the entire root system. 
2. Abies balsamea (fig. 10).—Under all the conditions of this 
experiment the roots grew downward and all were putting out 
laterals at the end of the experiment. At the water surface the 
roots behaved as in the case of Pinus Strobus. 
3. Picea excelsa (fig. 11) Throughout there was evident a 
decided tendency for the roots to assume an almost horizontal 
position. In some cases the roots penetrated somewhat below the 
water surface without showing any ill effects, although the rate of 
growth was greatly checked on entering the water. 
