THE TOXICITY TO FUNGI OF VAKIOUS OILS AND SALTS. 
19 
readily explained on the basis of chemical combination with the 
media. 
The length of time required to make an initial growth on different 
toxic media varies from a very few days up to seven weeks or more; 
check cultures usually start within two or three days. Table I 
illustrates this for a few preservatives. 
Table I 
[. — Time required by Fomes annosus on 0.2 'per cent concentrations and F. pinieola 
0.1 per cent concentrations to m.ahe initial growth from mycelium at 25° C. 
Preservative used. 
F. annosus. 
F. pinieola. 
Days. 
2 to 3 
20 
18 
15 
40 
Days. 
2 to 2 
24 
21 
18 
23 
53 
It is thus seen that no growth demonstrable to the naked eye on 
any of the concentrations mentioned occurred within a period of two 
weeks, and the error which would occur in discontinuing the tests 
at the end of 8 to 10 days, as several investigators have done, becomes 
very evident. 
RECORD OF TESTS CONDUCTED. 
A description of each of the 18 preservatives used, accompanied 
by individual tables and notes showing the rate, amplitude, and 
appearance of growth on the different concentrations, as compared 
with the check cultures, is given on the following pages. Under the 
heading "Concentration of the preservative" in each table the average 
radial distance to which the fungus has grown from the margin of the 
transfer at the end of the test is indicated by numerals, 1 the position 
of the first zero marking the killing point: Thus, 4 = 30 to 40 mm.; 
3 = 20 to 30 mm.; 2 = 10 to 20 mm.; 1 = 1 to 10mm.; = no growth. 
Sodium fiuorid. 
[Laboratory sample No. 1929. Purchased from Elmer & Amend, Chicago, 111.] 
Fungus. 
Tests. 
Times 
killing 
point 
veri- 
fied. 
Concentration of the preservative (per 
cent). 
Number. 
Duration. 
0.05 
0.1 1 0.15 
0.2 
0.25 
Check. 
9 
11 
Weeks. 
5 to 7 
1 I 4 
1 3 
3 1 2 
2 S ° 
1 

4 
4 
F . pinieola 
i It should be kept in mind that the growth rate designated as "4 " is not necessarily the same on different 
preservatives or different concentrations of the same preservative. All cultures "which have produced 
a growth of at least 30 to 40 mm. radius at the end of the test are included. Some of these mavhave reached 
this point in two to three weeks, as in the case of the checks, while others may have required the full test 
period; hence, the data as presented show only the relative retarding effect of the higher concentrations. 
