ON DUST AND DISEASE. 153 



of large chronic abscesses. In order to guard against the 

 access of atmospheric air, we used to draw off the matter by 

 means of a canula arid trocar, such as you see here, consist- 

 ing of a silver tube with a sharp-pointed steel rod fitted 

 into it, and projecting beyond it. The instrument, dipped 

 in oil, was thrust into the cavity of the abscess, the trocar 

 was withdrawn, and the pus flowed out through the canula, 

 care being taken by gentle pressure over the part to prevent 

 the possibility of regurgitation. The canula was then drawn 

 out with due precaution against the reflux of air. This 

 method was frequently successful as to its immediate object, 

 the patient being relieved from the mass of the accumulated 

 fluid, and experiencing no inconvenience from the operation. 

 But the pus was pretty certain to reaccumulate in course of 

 time, and it became necessary again and again to repeat 

 the process. And unhappily there was no absolute security 

 of immunity from bad consequences. However carefully 

 the procedure was conducted, it sometimes happened, even 

 though the puncture seemed healing by first intention, that 

 feverish symptoms declared themselves in the course of the 

 first or second day, and, on inspecting the seat of the abscess, 

 the skin was perhaps seen to be red, implying the presence of 

 some cause of irritation, while a rapid reaccumulation of the 

 fluid was found to have occurred. Under these circum- 

 stances, it became necessary to open the abscess by free 

 incision, when a quantity, large in proportion to the size of 

 the abscess, say, for example, a quart, of pus escaped, fetid 

 from putrefaction. Now, how had this change been brought 

 about? Without the germ theory, I venture to say, no 

 rational explanation of it could have been given. It must 

 have been caused by the introduction of something from 

 without. Inflammation of the punctured wound, even sup- 

 posing it to have occurred, would not explain the pheno- 

 menon. For mere inflammation, whether acute or chronic, 

 though it occasions the formation of pus, does not induce 

 putrefaction. The pus originally evacuated was perfectly 

 sweet, and we know of nothing to account for the alteration 

 in its quality but the influence of something derived from 



