424 
JAMES K. WILSON 
also that the different seeds are not sterilized in the same length of 
time, alfalfa requiring about six hours while wheat requires more than 
twice as long. 
Other tests of the efficiency of the method have been made. In 
one experiment thirty or more carefully selected seeds of each of the 
different kinds used were placed in test tubes and covered with a 
calcium hypochlorite solution containing approximately two percent 
chlorine. After treatment the seeds were transferred into test tubes 
on the surface of a medium which contained tap water and one per- 
cent each of agar and saccharose. After germination of the seed 
each tube was inoculated with a pure culture of Bacillus radicicola 
and placed in the greenhouse where it remained 45 days before 
examination. The seeds used and the time of treatment of each are 
as follows: 
Seed Time of Treatment 
Medicago sativa L 7 hours 
" his pida Gaertn 7 
" media ? 7 
" falcata L 7 
" lupulina L 7 
Melilotus alba Desr 7 
" indicata (L.) All 7 
" officinalis (L,) Lam 7 
Vicia villosa Roth 6}/2 
" sativa L 61^ 
" Faba L 3 
Lathy rus sylvestris L 5 
" sativus L 4 
The above treated seeds were planted in 184 test tubes which 
were reopened when inoculated. On examination only three tubes 
showed signs of contamination. Two of these were contaminated 
with molds while the other was with a bacterial organism. 
In addition to the foregoing tests the following data on the efficiency 
of the method were contributed by Dr. Knudson from experiments 
made on the organic nutrition of plants. These data are valuable 
because they indicate the thorough sterilization of the seed as is 
shown by the freedom of cultures from contaminations even after 
30 days or more of culture. The duration of immersion of the seed 
in the disinfectant and the culture media employed are indicated in 
the following table. 
