690 
VERANUS A. MOORE. 
media. Their disease-producing - powers, however, vary within 
wide limits. While these variations m physiological properties 
and pathogenesis are true for different cultures (species?), it has 
been found that there is a possibility of such variation in the 
subcultures of the same species. As wdth certain other bacteria 
their virulence is the first to suffer change. In differentiating 
species, therefore, the fact must not be overlooked, that the exist- 
ing characters and properties possessed by the streptococcus in 
hand may have been more or less influenced by its condi¬ 
tions of life. When, for example, two streptococci appear to 
be identical under the majority of tests, a slight deviation in 
a single property cannot be considered of too great a differential 
value especially if this particular manifestation is among those 
most subject to change. A fundamental difficulty in differenti¬ 
ating species among streptococci seems to be a lack of informa¬ 
tion concerning the possible variations brought about by different 
environments. The further difficulty of identifying any of the 
very large number of species which have been assigned specific 
means is due to the brevity of their description and the failure 
of the author to mention any character or property, or combina¬ 
tion of the same, which would distinguish it from others. How¬ 
ever, such deficiencies cannot well be avoided in the time of 
rapid accumulation of observation and the evolution of methods. 
At first it was thought to be sufficient to name a streptococ¬ 
cus from the disease, the lesion, or the animal in which it was 
found. Thus we have Streptococcus pyogenes , A. erysipelatos , 5. 
diphthe ; ice, S. equi and many others. Since the wide distribution 
of this genus on the normal mucous membranes of animals, in 
water, and in soil, and the frequency of their appearance in 
a great variety of lesions have become verified facts their 
“The only character or property found to be constant for all cultures of streptococci 
which I have isolated and studied has been their action on sugars. In every culture thus 
examined during the last six years the sugars commonly used (grape, cane, and milk) 
weie fermented, producing acids but no gas. The streptococci were rapidly destroyed in 
the acids produced. I have come to consider their action on sugars valuable in differenti¬ 
ating between streptococci which grow in very short chains and certain micrococci which 
often appear in this form. 
