146 I ELATIONSHIPS OF THE COCCACE^E 



Kurth (1891) described, under the name Str. conglom- 

 eratus, a type which he found often associated with scarlet 

 fever, and which was characterized by the formation in 

 broth of compact flakes of sediment composed of tightly 

 woven masses of chains, and by a high pathogenicity. 



Behring (1892) recognized four varieties of Str. longus, 

 the first yielding diffuse turbidity in broth, the second 

 forming a soft, slimy sediment, the third producing scaly 

 flocks of sediment (Kurth' s Str. conglomeratus), and the 

 fourth growing in balls made up of long chains tending 

 to cling to the walls of the tube. This fourth variety 

 of Behring's was described by Roscoe and Lunt (1892) 

 as Str. mirabilis. Behring's pupil, Knorr (1893), * ater 

 showed that these differences are highly variable; and pro- 

 duced from the same culture two races, differing markedly 

 in growth and in virulence, by successive cultivations and 

 animal inoculations. Pasquale (1893) a vear or tw0 ^ ater 

 made an elaborate comparative study of the streptococci, 

 using for his material thirty-eight different strains, repre- 

 senting almost all the forms which had at that time been 

 described. He confirmed the view that the most virulent 

 streptococci are in general those which form long chains 

 in broth,, tho all long-chained forms are not necessarily 

 virulent; and finally divided the organisms studied into 

 four classes : the short saprophytic streptococci (from faeces 

 and the alimentary tract), the long chain-formers of low 

 virulence, the long-chained virulent forms, and the short, 

 highly infectious forms (the diplococci of pneumonia and 



