1917] MOORE—CONIFEROUS FORESTS 155 
Experiments were also tried on the effect of these 3 soils on the 
growth of clover, wheat, and corn. Clover, as might be expected 
from its sensitiveness to acid, grew very poorly on the raw humus 
and mineral soil, but throve on the mild humus. In fact, it 
eventually died back and disappeared on the two former, lasting 
longer on the mineral soil than on the raw humus. Kubanka 
wheat did well on the mild humus, except for the shading, while on 
the raw humus and mineral soil it grew poorly. The dry weights 
per plant for Kubanka wheat sown June 24 and cropped Septem- 
ber 15 were 0.53 gm. for the mild humus as against 0.08 gm. on 
the raw humus, and only 0.03 gm. on the mineral soil. Corn 
(Golden Bantam) did so well on the mild humus that it had to be 
removed to prevent interference with the other experiments, 
while on the raw humus it produced only 0.09 gm. dry weight per 
plant, and on the mineral soil 0.13 gm. after growing for more 
than 3 months. The corn, it will be noticed, did better on the 
mineral soil than on the raw humus, indicating that this plant is 
affected more by acidity than by’ poor aeration. On the other 
hand, wheat grew better on the raw humus than on the mineral 
soil; on the former it frequently died down but came up again, 
while on the latter it showed less power of recovery. This would 
indicate that wheat is less sensitive to acid than to poor aeration. = 
Field observations on the root systems of spruce, fir,and white 
_ pine showed that detailed studies of roots would probably yield 
interesting results. Spruce roots form a dense mat in the raw 
humus or “duff,” a mat so dense that hardly a square ce timete 
under a spruce stand escapes. These rootlets keep i 
ee ene pleas as athe humus Sonn those i in the | 
a 
| — cory ke ‘enormous, cade cannot t fail to be : an 
. _Teproduction. “Fir roots a are | Cc all 
