RELATION OF SOME RUSTS TO THEIR HOSTS 
199 
In the use of the first, grains of yellow dent corn were cleaned and 
dropped into concentrated H2SO4 for ten minutes. They were then 
removed to a capsule of sterile distilled water and washed once or 
twice with sterile distilled water. They were then placed in sterile, 
moist chambers. This treatment with H2SO4 did not appear to 
injure the seed in any way. On the other hand, it hastened germina- 
tion of the seed. But it was not effective in killing the particular 
fungus spores which were present on these occasions and in nearly 
every case, fungi developed in the moist chambers. 
The use of HgCU was found to be much more satisfactory and it 
has been used entirely in this work where sterile corn plants were 
needed. The method used was to clean the seeds and drop them into 
.5 percent HgCU solution where they were left for thirty minutes. 
The HgCU solution was then poured off and replaced several times 
with sterile distilled water. The corn was then removed with sterile 
forceps and placed in large (4.3 X 25 cm.) sterile test tubes, which were 
placed in an incubator at 27°-30° C. This method gave very good 
results throughout the work and only a small number of contaminated 
seedlings were found. 
Wilson's calcium hypochlorite method was tried, but it did not 
give very good results. Ten grams of ''Acme" chloride of lime 
(bleaching powder) containing 30 percent chlorine were mixed with 
140 cc. of water according to Wilson's directions and maize was treated 
for 9 hours with the filtrate. Only very slight germination and poor 
seedlings were obtained by this treatment. The corn used however 
was a little over a year old and this may account for the failure, al- 
though it gave very good germination when treated with HgCl2, as 
stated above. To test this method still further corn was taken out of 
the sterilizing solution every hour for eight hours and placed in sterile 
moist chambers and then placed in an incubator at 27° C. Good 
germination took place with corn treated for one and two hours, but 
when treated beyond that time the germination was poor. All the 
moist chambers contained more or less contaminated seedlings. This 
method when used with oats and wheat gave good results, while HgCU 
as outlined above was unsatisfactory with oats and wheat. 
Although the number of disinfecting solutions used was not very 
great, yet the results obtained point to the uselessness of trying to 
obtain a disinfectant which will work for all seeds under all conditions. 
Not only will the kind of seed but also the age of the seed, the amount of 
