PYOGENIC BACTERIA. 



vented by the agents named in the proportion given : Nitric acid, 

 1 : 797 ; phosphoric acid, 1 : 750 ; boracic acid, 1 : 327 ; oxalic acid, 

 1 : 433 ; acetic acid, 1 : 720 ; citric acid, 1 : 433 ; lactic acid, 1 : 350 ; 

 benzoic acid, 1 : 400 ; salicylic acid, 1 : 655 ; iodine dissolved with 

 potassium iodide, 1:1,100; arsenite of potash, 1:733; mercuric 

 chloride, 1 : 81,400 ; chloral hydrate, 1 : 133 ; carbolic acid, 1 : 814 ; 

 thymol, 1 : 11,000 ; resorcin, 1 : 122 ; hydrochinon, 1 : 353 ; kairin, 

 1 : 407 ; antipyrin, 1 : 26 ; muriate of quinine, 1 : 550 ; muriate of 

 morphia, 1 : 60. For the destruction of vitality very much larger 

 amounts are required. In Bolton's experiments (1887) a one-per-cent 

 solution of carbolic acid was successful after two hours' exposure, 

 but two per cent failed to completely destroy vitality in the same 

 time ; one per cent of sulphate of copper was also successful, and but 

 a single colony developed after exposure to a solution of 1 : 200. In 

 the experiments of Gartner and Plagge the Staphylococcus aureusin 

 bouillon cultures is said to have been killed in a few seconds (eight) 

 by a solution of mercuric chloride of the proportion of 1 : 1,000 ; Behr- 

 ing found it was killed by the acid sublimate solution of La Place, 

 in the proportion of 1 : 1,000, in ten minutes ; Tarnier and Vignal 

 found that a solution of 1 : 1,000 was successful in two minutes. 

 Abbott (1891) has shown that in the same culture there may be a 

 considerable difference in the resisting power of the cocci, and that 

 while frequently all are destroyed in five minutes by a 1 : 1,000 solu- 

 tion, it occurs quite as frequently that some may survive after an ex- 

 posure of ten, twenty, and even thirty minutes. 



Pathogenesis. Subcutaneous inoculation with a small quantity 

 of a culture of Staphylococcus pyogenes aureus is without result in 

 rabbits, guinea-pigs, or mice, but when a considerable quantity is 

 injected beneath the skin of a rabbit or a guinea-pig an abscess is 

 produced, which usually results in recovery, but may give rise to 

 general infection and the death of the animal. Injection into a 

 vein or into the cavity of the abdomen in the animals mentioned 

 usually induces a fatal result within a few days. The most charac- 

 teristic pathological changes are found in the kidneys, which con- 

 tain numerous small collections of pus and under the microscope 

 present the appearances resulting from embolic nephritis. Many of 

 the capillaries and some of the smaller arteries of the cortex are 

 plugged up with thrombi consisting of micrococci. Metastatic ab- 

 scesses may also be found in the joints and muscles. The micro- 

 cocci may be recovered in pure cultures from the blood and the 

 various organs ; but they are not numerous in the blood, and a sim- 

 ple microscopical examination will often fail to demonstrate their 

 presence. 



Animals frequently survive the injection of a small quantity of 



