148 REporRT OF DEPARTMENT OF BACTERIOLOGY OF THE 
In other trials it was found that additions of 0.1% and less 
of phenol failed to sterilize and, on the other hand, additions 
of 5% or more totally inhibited the activity of the enzym. The 
phenol was added to the culture in these experiments four days 
before the enzymic activity was tested. . 
THY MOL. 
This proved less satisfactory as a germicide than phenol, 
but chiefly, we think, because of its slight solubility and slow 
diffusion in the broth. If the alcoholic solution is used the 
thymol is precipitated upon contact with water, hence there 
is no gain. Our trials have shown that powdered thymol, 
which floats on the surface of a broth culture, will sterilize 
the surface layer, but that where the culture has stood with- 
out shaking, living organisms persist, at least for many days 
in the deeper parts of the broth. For this reason even large 
amounts of thymol will fail to sterilize in the absence of agi- 
tation, whereas sterility can be secured with small amounts 
by thorough shaking. The following experiments will serve 
to show this. 
A large excess of thymol (2%) was added to each of ten 
broth tube cultures eight days old and a small amount (about 
0.2%) to each of ten similar tubes. All of these were left 
without agitation. Transfers made on the eighth day there- 
after showed living organisms in four of the tubes containing 
the larger amount of thymol and in five of those with the 
smaller amount. On the tenth day living organisms remained 
in three tubes of each series. In another series a crystal of 
thymol equalling about 0.2% of the broth was added to each 
of three ten c. c. broth tube cultures four days old and a tiny 
crystal of about one-fourth this size to each of three other 
similar cultures. These were all thoroughly shaken. Trans- 
fers from these tubes on the second day thereafter showed 
living organisms in all three of these containing the lesser 
amount, but the others were sterile. In all cases pieces of 
sterile carrot inserted into tubes sterilized by thymol have 
been quickly softened without evidence of inhibition. 
