114 A. H. Graves, 
Not only the evident carefulness with which he has conducted 
his experiments, but also the variety of species and number of 
specimens used, joined with his very positive results, should put at 
rest all doubt as to the importance of the absorptive role of the 
roots of submerged plants. 
On the other hand, Pond’s experiments fail to show conclusively 
whether or not water and dissolved salts are absorbed by the part 
of the plant above the soil—a condition which is indicated by the 
reduction of the xylem area of the root. 
Too much emphasis, therefore, must not be laid upon the ab- 
sorbing capacity of the root, as is shown by the following con- 
siderations :—1. the absence of transpiration as we are acquainted 
with it in land plants; 2. the probable absorption by the parts of 
the plant above the soil of nutrient solutions from the surrounding 
water; 3. connected with these two conditions a reduction of the 
xylem area to a few tracheae of rudimentary nature; and 4. the 
total lack of branches and the slenderness of the roots. 
In brief, the absorption carried on by the roots of submerged plants 
and the importance of this function in the economy of the plant is 
much greater than is implied by Schenck, as the experiments of 
Pond demonstrate; but, on account of the peculiar environmental 
conditions of submerged plants, it can never equal in importance the 
absorption of the roots of land plants. 
