1906] TRANSEAU—BOGS OF THE HURON RIVER VALLEY 22 
that the experiments should extend over a series of years in the 
case of the shrubby forms, the problem becomes still more com- 
plicated. 
Cold bog water Cold nutrient solution 
Warm nutrient solution Warm bog water 
Pic. 12.—Average plants from the several cultures of Indian corn, From photo- 
graphs. ‘ 
In order to test the relative effects of humous acids (of the con- 
centration found in the bogs of this vicinity) and low substratum 
temperatures, experiments were made in the form of water cultures 
