STREPTOCOCCI 39 



possessed by the streptoccocus in hand may have been more 

 or less hifluenced by 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 manifes- 

 tation is among those most subject to change. A fundamental 

 difficulty in differentiating species among streptococci seems to 

 be a lack of information concerning the possible variations 

 brought about by different environments. The further diffi- 

 culty of identifying any of the very large number of forms 

 which have been assigned specific names is due to the brevitj^ 



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4. 3. 6. 



Fig. 7. Si.v forms 0/ streptococci, i. Long chains consisting oj 

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

 shorter chains in luhich the segments are arranged in pairs. The size 

 of the individual seginents is considerably larger than those in the long 

 chains, j. Short and longer chains zvhere the segments are oval with 

 the long diameter perpendicular to the long a.x-is of the chain. 4. Long 

 interlaci?ig chains. 5. Short and longer chains with one or more seg- 

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

 in two planes. This form of division has been observed in afezv cases. 

 The dividing in tzvo planes is an exception zvhich is not satisfactorily 

 explained, x about woo. 



