562 
BOTANY: A. R. HAAS 
organic acids and that the quantity of detectable acids is very small, 
lying below the limit of sensitivity of litmus. Czapek^ concluded that 
roots gave off K, Ca, Mg, HCl, H2SO4 and H3PO4 to water. Stocklasa 
and Ernest^ have been unable to find K or H3PO4 in root excretions. 
They found that CO2 is the only gaseous product in root excretions, 
with a possibihty of H. No free mineral acids were considered to be 
present in root excretions, and organic acid excretion was considered to 
occur only when the oxygen percentage was low. Breazeale and Le- 
Clerc*^ state that the roots of wheat seedlings in distilled water excrete 
acids other than CO2. 
In some of the investigations mentioned above no control of distilled 
water without seedlings was run, and the amount of alkali used to 
titrate a boiled sample of distilled water, in which seedlings had grown, 
appears to be approximately the amount required to cause coloration 
of the indicator in such a volume of neutral solution. Seeds were in 
some cases in contact with the solution and might have given off acid 
from dead cells. In some cases it appears certain that dead cells of the 
roots affected the results. The use of carbon black by some investi- 
gators introduces an unknown factor which may alter the results. 
The experiments of the writer were made upon early sweet corn by 
soaking the seed for several hours and then germinating it on moist 
filter paper in porcelain pans covered by inverted pans. When the 
roots were about one to one and one-half inches long, the seedlings 
were placed in the water cultures. Glass tumblers were steamed and 
thoroughly cleansed, and the outside covered with paper to prevent 
the growth of algae. Dental napkins, in which one rather large and 
numerous small holes were cut, were used to cover the tumblers after 
the distilled water was run in.^ The cloth covers were drawn tight by 
the use of string and never were allowed to come into contact with the 
solution. The larger hole was used to run in more water as evapora- 
tion proceeded while in the small holes the seedling roots were placed. 
Covers of various kinds were used because the water evaporated too 
rapidly from the tumbler through the cloth. The same kind of cover, 
with a thin coat of high grade paraffine, prevented much evaporation 
since the large corn seed covered the hole through which the root had 
been thrust. Also no tying of the cover was necessary; simply folding 
down the overhanging edges of the cover about the sides of the tumbler 
sufficed. Great care was taken to use only roots which had no dead 
cells (except those of the root cap). 
Experiment 1. Twenty-five seedlings were grown in each tumbler in 
190 cc. of distilled water. Controls were set up similar in every re- 
