28 BACTERIOLOGY 



importance of these observations; many claimed that 

 micro-organisms were normally present in the blood and 

 tissues of the body; and some even urged that the organisms 

 seen in diseased conditions were the result rather than the 

 cause of the maladies. It is hard'Jy necessary to do more 

 than say that both of these views were purely speculative, 

 and have never had a single reliable experimental argument 

 in their favor. Billroth and Tiegel, who held to the former 

 opinion, did endeavor to prove their position through experi- 

 mental means; but the methods employed by them were of 

 such an untrustworthy nature that the fallacy of deductions 

 drawn from them was very quickly made manifest by subse- 

 quent investigators. Their method for demonstrating the 

 presence of micro-organisms 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 



