2O6 BACTERIOLOGY. 



cells, and spreading from the point of inoculation, 

 causes death in about three days (Fig. 73). The 

 cocci are absent from the blood and internal 

 organs. These observations were made after the 

 injection of putrid fluids in the ear of mice, and 

 a pure infection was obtained by the inoculation 

 of field-mice, which have an immunity from bacil- 

 lary septicaemia. 



FIG. 73. STREPTOCOCCUS OF PROGRESSIVE TISSUE NECROSIS IN MICE. 

 (a) Necrotic cartilage cells, and () Chains in masses ; (c) Chains 

 isolated [after Koch]. 



Streptococcus perniciosus (Parrot disease}. 

 Cocci, singly, in chains, and in zoogloea have 

 been described in connection with a disease of the 

 grey parrot (Psittacus erithacus).* This disease 

 is fatal to about 80 per cent, of these parrots 

 imported to Europe. They suffer from diarrhoea 

 and general weakness ; their feathers are ruffled, 

 their wings hang loosely, and their eyelids close ; 

 convulsions set in, and death follows. At the 



* Wolff, Vir 'chow's Archtv. 1883. 



