Marcu 8, 1912] 
media in which we have attempted to 
study them. With the adoption of media 
of definite chemical composition for ma- 
king our determinations and measure- 
ments, the physiological characters of the 
bacteria will assume the importance of the 
morphological characters of higher organ- 
isms. Then and then only shall we able to 
arrive at a natural classification of bac- 
terial species which shall express for us 
their true relationship. 
With the adoption of such accurate 
chemical tests of the physiological char- 
acters of the bacteria much of the present 
apparent variation will pass away and we 
shall find the physiological characters of 
the different groups as stable as any of 
their morphological characters. And 
what little variation remains—and we shall 
always find some variation as long as we 
deal with living organisms—we can 
handle easily by the method of biometry. 
For, as you know, the methods of statis- 
tical variation can apply only in char- 
acters which are measurable. 
This matter of better methods of spe- 
cies identification and a new taxonomy will 
be one of the first outcomes of the adop- 
tion of simple chemical culture media. 
Another important result will be the 
inereased ease with which certain biochem- 
ical problems in bacteriology can be at- 
tacked. Think for a moment of our en- 
deavors to find a suitable method of iso- 
lating the colon bacillus. Litmus-lactose- 
agar, endo, esculin, neutral red, mala- 
' chite green, phenol, bile and bile salts and 
their various combinations are but expres- 
sions of our total ignorance of the chem- 
istry involved. The problem should be at- 
tacked in an entirely different way. First, 
we should determine the simplest synthetic 
medium upon which the colon bacillus will 
erow rapidly and well. Then by adding 
to it the chemical body which is the in- 
SCIENCE 
361 
hibiting agent in the phenol or in the bile 
we ought to have the ideal medium for 
colon isolation. A beginning along this 
line has been made by Dolt* in his am- 
monium lactate, glycerin and malic acid 
media. But further work must be done 
until we have a simple synthetic substitute 
for the complex, variable and inconven- 
ient media upon which we depend so much 
at present. 
And then take the differentiation of the 
colon and typhoid groups by cultural 
characters. There must be certain chem- 
ical differences inherent in these organ- 
isms which could be easily determined by 
the use of synthetic media adapted to 
each organism. 
Another desideratum is a simple syn- 
thetic medium to be used as a substitute 
for blood serum when used for the diag- 
nosis of diphtheria. We have to depend 
at present upon the uncertain and unsatis- 
factory supply of blood from the abattoirs. 
How much better would it be to find a 
chemical substitute which would be just as 
certain for diagnosis and much easier to 
prepare? I believe that such a substitute 
will soon be forthcoming. 
We have been gradually accumulating 
a knowledge of a considerable number of 
important chemical products which are 
produced by the activities of bacteria 
either by synthesis or decomposition. 
Many of these substances are of great im- 
portance. Many are produced only as far 
as we know at the present time by bac- 
teria. How little at present we know of 
the. chemistry of these products! How 
much can be learned by a study of the 
formation of these substances in culture 
media of known composition! The chem- 
*Dolt, M. L., ‘‘Simple Synthetic Media for the 
Growth of B. coli and for its Isolation from 
Water,’’ Journal of Infectious Diseases, V., 1908, 
616. 
