DISTRIBUTION OF STREPTOCOCCI 43 



rapid proliferation in native soil made favorable for their ex- 

 cessive increase by the conditions produced by the true etio- 

 logical factors. Their natural distribution is so wide and 

 their virulence so capricious that a secondary invasion, which 

 seems always to be possible, renders the fixing of etiological 

 responsibility upon a streptococcus isolated from any diseased 

 tissue a somewhat difficult task. The problems in this con- 

 nection which concern us most and which need more extended 

 investigation pertain (i) to the determination of the parasitic 

 possibilities of streptococci existing in nature, i. e., those ordi- 

 narily considered as saprophytes and (2) to the distinction, if 

 it exists, between streptococci that are able to produce local 

 inflammatory processes leading to suppuration and those which 

 produce highly infective and rapidly spreading diseases, such 

 as erysipelas and strangles. 



In view of the confusion respecting species in this genus, 

 the identity of streptococci isolated from the lesions in the 

 various diseases which have been attributed to streptococci is, 

 at the present time, a matter of some uncertainty. There is 

 also considerable skepticism concerning the primary etiological 

 significance of the streptococci in a number of diseases in 

 which they have, heretofore, been assigned as the cause. 

 Recent investigations, especially those of Lignieres, tend to 

 the conclusion that they are often secondary invaders in cer- 

 tain of these diseases. Petruschky has pointed out analogous 

 cases in human infections in showing that streptococci play an 

 important role as secondary invaders in human diphtheria, 

 scarlatina and tuberculosis. 



Pathogenesis. In the absence of verified results to prove 

 the non-specific relation of streptococci to the diseases which 

 have with reasonable certainty been attributed to the activities 

 of this genus of bacteria, these affections are tentatively 

 included among the specific streptococcic maladies. It is very 

 important, especially when the use of antistreptococcic serums 

 are in question, to take into account the apparently large 

 number of forms, or species, commonly included in the general 

 statement of a streptococcus disease or infection. In 1897, 



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