28 STREPTOCOCCI 



or less influenced b}- its conditions 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 great differential value especially if this particular manifesta- 

 tion is among those most subject to change. A fundamental diffi- 

 culty in differentiating species among streptococci seems to be a 

 lack of information concerning the possible variations brought 

 about by different environments. The further difficulty of 

 identifying any of the very large number of forms which have 

 been assigned specific names is due to the brevity- of their de- 

 scription and the failure of the author to mention any character 

 or property, or combination of the same, which would distin- 



G. 



Fig. 4. Six' forms of streptococci, i . Long chains consisting of 

 small segments arranged with equal spaces between them. 2. Long and 

 shorter chains in which the segments are arranged in pairs. The size of 

 the individual segfnents is considerably larger than those in the long 

 chains, j. Short and longer chains where the segments are oi'al zvith the 

 lotig diameter perpendicular to the long axis of the chain. 4. Long 

 interlacing chains. 5. Short and longer chains with one or tnore seg- 

 ments very much larger than the others. 6. Chains shozving divisions 

 in two planes. This form of division has been observed i7i a few cases. 

 The dividing in two planes is an exception which is not satisfactorily 

 explained . X about 1000. 



