Roots and its Influence on the Ecesis of Plants in Swamps . 31 
merged is greater than under similar conditions in peat. This appears to be 
due for the most part to a greater lack of oxygen in Sphagnum than in 
peat. A similar relation exists between plants in peat and in soil with the 
roots submerged. 
(4) When the water is aerated plants, are able to endure root sub- 
mergence as long as aeration is maintained. The roots show some retarda- 
tion in growth, but remain alive. 
(5) Ranunculus abortivus i R. scelevatus , and Cyperus alternifolius 
grown in submerged soil show a greater growth of the entire plant than 
when grown in moist soil. The ability to grow with the roots submerged is 
undoubtedly due to the presence of aerenchyma. The reduction of the 
growth of the plants in moist soil is caused by the inability of the roots to 
absorb sufficient water under such conditions. 
(6) Land plants with submerged roots show more or less pronounced 
wilting after one to three days. If submergence is prolonged the leaves 
become yellow and soon fall. 
(7) Land plants with submerged roots do not show these effects, or 
only to a slight extent, in aerated water. 
(8) Philotria placed in water with good light causes a decrease in 
carbon dioxide and an increase in oxygen content of the water. 
(9) Plants in soil from which oxygen is excluded show wilting, etiola- 
tion, and loss of leaves. The effects appear in the same order and same 
time as in plants with the roots submerged. 
(10) Plants with submerged roots show a temporary increase in 
transpiration, which is soon followed by a sharp decline as compared with 
the transpiration of plants grown in moist soil. 
(11) The reduction in transpiration precedes wilting. It precedes 
etiolation and loss of leaves by two to four days. This indicates that 
absorption is reduced below the amount demanded by transpiration. 
(12) When aeration is provided, the development of plants is essentially 
as good with swamp water as with nutrient solution. -Plants with swamp 
water are somewhat smaller. The difference is somewhat more evident 
when the plants are deprived of reserve food. This indicates that the 
difference in growth is correlated with the food supply. 
(13) The oxygen content of lake water is essentially the same as that 
of tap or distilled water under similar conditions. The oxygen content of 
swamp water decreases from the Car ex stage to the Chamaedaphne- Andro- 
meda and Larix-Picea stages. 
(14) The carbon dioxide content shows a corresponding increase 
through the same stages. The increase is due to the decomposition of 
organic matter by which carbon dioxide is liberated. 
(15) The adjustment of the roots of swamp plants to the water-level is 
due to the necessity of securing a sufficient supply of oxygen. This 
