30 BACTERIOLOGY 



presence of microorganisms in normal tissues was to remove 

 bits of organs from the healthy animal body with heated 

 instruments and drop them into hot melted paraffin. They 

 held that all living organisms on the surface of the tissues 

 would be destroyed by the high temperature, and that if 

 decomposition should subsequently occur it would prove that 

 it was the result of the growth of bacteria in the depths of 

 the tissues to which the heat had not penetrated. Decom- 

 position did usually set in, and they accepted this as proof of 

 the accuracy of their view. Attention was, however, shortly 

 called to the fact that in cooling there was contraction of 

 paraffin, resulting usually in the production of small rents 

 and cracks in which dust, and bacteria lodged upon it, 

 could accumulate and finally gain access to the tissues, 

 with the occurrence of decomposition as a consequence. 

 Their results were thus explained after a manner analogous 

 to that employed by Spallanzani, in 1769, in demonstrating 

 to Treviranus the fallacy of the opinion held by him and the 

 accuracy of his own views, viz., that it was always through 

 the access of organisms from without that decomposition 

 primarily originated. (See page 22.) 



Under careful precautions, to which no objection could 

 be raised, the experiments of Billroth and Tiegel w^re 

 repeated by Pasteur, Burdon-Sanderson, and Klebs, but 

 with failure in every instance to demonstrate the presence 

 of bacteria in the healthy living tissues. 



The fundamental researches of Koch (1881) upon patho- 

 genic bacteria and their relation to the infectious diseases 

 of animals differed from those of preceding investigators 

 in many important respects. The scientific methods of 

 analysis with which each and every obscure problem was 

 met as it arose served at once to distinguish him as a pioneer 



