BACTERIA AS THE CAUSES OF DISEASE. 81 



micro-organism. The blood or pus was diluted many times 

 with water, the sediment was washed again and again, each 

 time being allowed to settle at the bottom, after which the 

 supernatent fluid was found to have no effect in producing 

 any disease, whilst the sediment which contained pus organ- 

 isms and " fine granulations " almost invariably set up the 

 disease process. The virus must accordingly, these observers 

 thought, be a solid poison, and must be looked upon as a 

 particulate body. These observations thus confirmed, to a 

 certain extent, Hallier's suggestion that a micrococcus or 

 a bacterium was the cause of most specific infective diseases. 



From this time onwards a large number of observations were made on 

 various infectious diseases and micro-organisms. Micrococci were found in 

 diphtheria, in scarlet fever, in rinderpest, septicaemia, and in other specific 

 infective conditions, though Traube, in 1864, had made what might be con- 

 sidered the first practical application of what had been discovered to be an 

 important pathological condition when he demonstrated the fact that, if 

 bacteria found their way into the bladder by means of a dirty catheter, a 

 severe attack of inflammation of the bladder followed an observation which 

 was supplemented by Klebs, who demonstrated the connection between 

 small abscesses in the kidney and the introduction of micro-organisms into 

 the bladder. But with all these records there was very little of definite 

 value to demonstrate the causal relationship between bacteria and disease, 

 and even when fragments of diphtheritic membrane and of the wall of 

 abscesses were introduced under the skin of an animal, and gave rise to 

 both local and constitutional symptoms, there was no proof forthcoming 

 that these were due to the micro-organism, and not to such special chemical 

 products as had already been separated from putrid and diseased materials. 

 Panum had demonstrated, in 1856, that it was possible to obtain from decay- 

 ing flesh infusions an extremely poisonous substance, and his results were 

 confirmed by numerous observers, some of whom succeeded in combining 

 with acids the "basic" substance that Panum had separated; the sul- 

 phate of this base when injected into frogs proved fatal, and eventually 

 Zulzer and Sonnenschein prepared what they described as a septic alkaloid 

 which was stable in character, and in its reactions resembled most remark- 

 ably the vegetable alkaloids, atropin and hyoscyamin. It was natural that 

 as these materials could be separated by chemical means from diseased and 

 putrefying materials, they should be looked upon as the primary and real 

 etiological factors in the transmission of disease. In 1871, however, Reckling- 

 hausen, turning his attention to bacteria, was able to show that in the organs 

 of patients affected with various infective diseases (such as blood-poisoning, 

 and puerperal fever, typhoid fever, acute articular rheumatism, gangrene of 

 the lung) small accumulations of micrococci were present, and that these 

 were probably the cause or the agent by which deposits of the abscesses or 

 gangrenous patches occurred in different parts of the body and in different 

 organs. These micrococci were described as having an exceedingly sharp 

 outline, as being extremely resistant to strong acids and alkalies, and, in 

 fact, as being in most other respects like those that had been described as 



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