1913] RIGG—EFFECT OF BOG WATERS 317 
The expression “normal root hairs” used in this paper with 
reference to Tradescantia (the species common in greenhouses, and 
known as wandering Jew) means such root hairs as grow on the 
roots of cuttings in tap water. These hairs cover the entire surface 
of the root even when it reaches a length of 7o mm. or more. They 
are almost uniformly distributed, 4 mm. or more in length, mostly 
straight, and appear to the naked eye like somewhat silky fibers. 
_ Over 200 specimens of this plant grown in tap water have been 
examined and there has been found practically no variation from _ 
this description. 
Investigation 
In October 1909 experiments were begun on the germination of 
wheat, corn, beans, and peas in moist peat and between sheets of 
moistened blotting paper. It was found that these seeds germi- 
nated just as readily when the moisture was furnished by bog water 
as when it was furnished by tap water. 
In the fall of 1910 Ledum groenlandicum and Kalmia glauca 
were propagated by cuttings in both bog water and tap water in the 
laboratory. Young roots from both of these species from both 
inds of water were examined and found to be entirely devoid 
of root hairs. Some of the roots examined were produced on old 
roots formed before the plants were removed from the bog and some 
were produced on stems. 
TRANSEAU (10) found root hairs absent in Oxycoccus macro- 
carpus. He also found that the roots of Larix laricina were 
“composed of mycorhiza,’ and that their cortical tissues were 
early destroyed by a fungus. When he grew these plants in a well- 
aerated culture solution ‘‘normal roots with root hairs were pro- 
duced.” 
Covitte (1) found Vaccinium corymbosum to be devoid of 
root hairs. He found also that the walls of the epidermal cells 
of the roots were 1.3-2.5 thick, this being four to six times as 
thick as the walls of epidermal cells of wheat roots. He computes 
that a given section of wheat root presents about ten times as much 
absorptive surface as a section of blueberry (Vaccinium corym- 
bosum) root of the same area. 
