158 SUPPURATION AND ALLIED CONDITIONS. 



formed to determine whether it could be produced by 

 simple chemical substances, such as croton oil, nitrate of 

 silver, mercury, etc. In these experiments various means 

 have been employed to ensure the absence of bacteria. In 

 some cases the chemical substance to be tested was placed 

 in a closed glass capsule, which, after being sterilised, was 

 inserted in the tissues and was not broken until the external 

 wound had healed up ; in other cases the capsule was made 

 with pointed ends, so that it could be moved in the body 

 of the animal to another part, and there broken. The 

 general conclusion obtained by independent observers is 

 that in these conditions suppuration usually does not 

 follow, but that in certain animals and with certain chemical 

 substances it may occur, the pus which forms showing no 

 organisms on bacteriological examination. Such suppura- 

 tion, however, never produces secondary abscesses in other 

 parts, and it is still questioned by some whether the pus 

 produced really corresponds histologically and chemically 

 with pus naturally produced. Buchner showed that sup- 

 puration could be produced by injections of dead bacteria, 

 for example, sterilised cultures of bacillus pyocyaneus, 

 tubercle bacillus, and various others. The question, how- 

 ever, is now rather of scientific than practical interest, and 

 the general statement may be made that practically all cases 

 of acute suppuration met with clinically are produced by 

 the action of living micro-organisms. 



LESIONS IN THE HUMAN SUBJECT PRODUCED BY 

 PYOGENIC BACTERIA. 



The following general statement may be made with 

 regard to the occurrence of the chief organisms mentioned, 

 in the various suppurative and inflammatory conditions in 

 the human subject. It may also be noted that acute 

 catarrhal conditions of cavities or tubes are in many cases 

 also to be ascribed to their presence. 



The staphylococci are the most common causal agents in 



