PECTIC MATERIAL IN ROOT HAIRS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 286 
‘CAROLINE G. Howe 
It has been observed for some time that many soils show some 
acidity, that plants are able to take up much more mineral matter 
than can easily be extracted from soil, and also that although 
fertilizers are made up of soluble salts, the virgin soils are composed 
largely of difficultly soluble salts, and after they have been culti- 
vated a few years, yield as full crops if not fuller than those treated 
with ordinary fertilizers. This has given rise to the question 
whether there may not be something in the structure of the root 
hair which enables it to change the difficultly soluble salts to such a 
form that they can be dissolved and taken into the plant; and 
since root hairs are so ephemeral, any chemical effect they may 
have upon the soil will not be present very long in one place. 
Since many soils were found to be somewhat acid, and yet most 
plants cannot grow in an acid medium, two explanations were 
offered for this phenomenon; first, that there was an acid in the 
soil which, for lack of a better name, was called humus acid; and 
secondly, that negatively charged colloidal particles either in the 
plant tissues or in the soil broke up the salts and released the acids 
into the soil. 
BAUMANN and GULLY (cited by SKENE 6) investigated this 
matter with peat and mosses, and found that when put into a 
sodium chloride solution, these plants were able to absorb the 
positive ion and thus release the chlorine, which, combining with 
the hydrogen ion, made hydrochloric acid. SKENE (6) made similar 
tests upon sphagnum, using copper chloride solution, and found 
that the moss had taken up the copper, releasing the chlorine, 
which again formed hydrochloric acid. WxELER (8) also tested 
the higher plants, such as the needles of the pine, the leaves of the 
horse chestnut, American oak, and yellow lupine, and found that 
they were all acid, and concluded that the decaying vegetation 
313] [Botanical Gazette, vol. 72 
