594 THE STREPTOCOCCI OF MAN 



Chiefly as the results of the experiments of Marmorek and Aronson the 

 opinion gained ground that there was but a single species of streptococcus 

 which according to the conditions prevailing might cause any one of a number 

 of different pathological conditions. 



[Andre wes and Border from a study of the bio-chemical reactions, morpho- 

 logical appearances and other characteristics of a large number of streptococci 

 from various sources have provisionally but without any idea of finality 

 classified these organisms into six groups (vide. p. 601). 



[Reviewing these conflicting opinions, it may be said that all observers are 

 at least agreed that there are many and important characteristics possessed 

 by all streptococci in common, and that the controversy hinges on the question 

 whether the differences which undoubtedly exist between various strains are 

 to be regarded as of minor importance as those who consider all streptococci 

 identical maintain or whether as the other side insists these differences are 

 of capital importance necessitating a division of the streptococci into species. ] 



At the moment it would seem best to take up the position that in the case 

 of the streptococci, as in that of the cholera vibrio, there are several races 

 one might almost say species, but an authoritative definition of the term is 

 lacking. 



[The subject is not merely one of academic interest but is from the point 

 of view of serum therapy of considerable practical importance.] 



It is not within the province of this book to discuss the arguments brought 

 forward by the opposing theorists the subject is still one of the most acutely 

 discussed problems in bacteriology but the differences between various 

 strains of streptococci will have to be noticed as will also the facts upon 

 which the two sides base their conclusions. 



SECTION I. EXPERIMENTAL INOCULATION. 



Generally speaking, streptococci isolated from man, even from severe infections, are 

 only slightly virulent for animals. 1 Consequently, the first inoculation of a streptococcus 

 of unknown virulence should be made with a large dose of culture either into the veins 

 or into the peritoneal cavity. The virulence of the organism for animals is rapidly 

 increased by passage through animals. 



Rabbits.- Rabbits are the most useful animals for the study of the experi- 

 mental disease. For purposes of inoculation cultures 2 or 3 days old should 

 be used (vide infra). 



A. Sub-cutaneous inoculation. As a rule, the animal is inoculated beneath 

 the skin of the ear ; this enables the progress of the lesion to be readily 

 observed. According to the virulence of the organism an inoculation of 

 10-20 drops of culture will produce one of the following results : 



(a) A small abscess. 



(b) A temporary erysipelatous blush. 



(c) An erysipelas involving the whole ear, possibly becoming phlegmonous 

 but not ending in generalization. 



(d) A phlegmonous erysipelas followed by suppurative arthritis and ending 

 in death in 15-30 days. Streptococci cannot, as a rule, in this case be found 

 either in the articular pus or in the blood after death. 



(e) A rapidly fatal septicaemia ending in death in a few days. Streptococci 

 can be found in the blood post mortem. 



B. Intra-venous inoculation. Inoculation of a virulent streptococcus into 



[ x But see later on under the heading of " Virulence." Streptococci from severe human 

 infections are generally of the pyogenes variety and are pretty virulent for mice at 

 least (Andrewes).] 



