PHYSIOLOGICAL PROPERTIES OF BOG WATER. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
BurRTON EDWARD LIVINGSTON. 
(WITH THREE FIGURES) 
ALTHOUGH it has been shown (1) that water from the bogs of the 
northern United States contains solutes to such a very small amount 
that its osmotic pressure is generally not appreciably above that of 
the river swamps and lakes of the same region, still the generally 
observed xerophilous character of bog vegetation may be due to small 
amounts of dissolved substances of such nature that they affect the 
plants chemically through toxic stimulation. Having found that 
metallic ions affect the vegetative growth of the polymorphic 
Stigeoclonium with which the author has been experimenting for 
some time (2), and that the effect thus produced is identical with 
- the response of the alga to high osmotic pressures, it was suggested 
that this alga might be used as an indicator in a study of the physi- 
ological properties of bog waters. In accordance with this suggestion, 
natural waters of a number of different types were collected in bottles, 
filtered through filter paper, and tested as culture media for the 
alga. The result of these tests is, briefly, that many bog waters act 
upon the plant like poisoned solutions. Details of the work are 
given in the following pages. 
The form of Stigeoclonium here used has already been shown 
(2-6) to take either of two forms according to the medium in which 
it is grown. In solutions of low osmotic pressure at ordinary tem- 
peratures it assumes the form of branching filaments composed of 
cylindrical cells. In the same solutions at a temperature slightly 
above the freezing point of water, and at ordinary temperatures 1) 
solutions similar to these but poisoned with certain metallic salts, as 
well as at ordinary temperatures in solutions of high osmotic pressure; 
the plant takes the palmella form, in which the cells are spherical or 
nearly so and lie in the medium singly or in irregular groups- If 
348 [may 
