THE PHILIPPINE 
Journal of Science 
C. Botany 
Vol. VIII FEBRUARY, 1913 No. 1 
THE RELATION OF THE SUBSTRATUM TO THE GROWTH OF 
ELODEA 
By William H. Brown 
(From the Botanical Section of the Biological Laboratory, 
Bureau of Science^ Manila, P. I.) 
INTRODUCTION 
The slig-ht development of conducting tissue in many water 
plants, together with the thinness of the epidermis, has led to a 
widespread belief that most submerged plants take nutrient salts 
largely if not entirely from the water in which the stems and 
leaves are floating, and that the roots serve only as organs of 
attachment. The conclusion that submerged plants absorb nu- 
trient salts through the epidermis of the leaves and stems is, 
however, as pointed out by Pond,' based on a priori rather than 
experimental grounds. 
Several observers have found that colored solutions will rise 
in the stems of certain submerged plants if the cut ends of the 
stems are placed in the solutions ; see Pond." Thoday and Sykes ^ 
report a rise of a solution of eosin in a stem of Potamogeton 
lucens at the rate of 9.5 cm a minute. Pond states that the 
amphibious plant Ranunculus aquxitilis var. tHchophyllus absorbs 
* Pond, R. H. The Biological Relation of Aquatic Plants to the Sub- 
stratum. Rept. U. S. Comm. Fish and Fisheries 29 (1905) 483-526. 
'L. c. 
* Thoday, D. & Sykes, M. G. Preliminary Observations on the Trans- 
piration Current in Submerged Water-plants. Ann, Sot, 23 (1909) 635-637. 
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