140 THE GERM THEORY OF DISEASE. 



arouse the resistant energies of the tissues. Surely, if the 

 tissues are capable of forming, by reason of irritation, a 

 secretion that will digest a piece of ivory that has been thrust 

 into the flesh, which has been proven by direct experiment, 

 we should expect this kind of resistance to be offered to the 

 development of disease-producing germs. 



Facts of a very decisive nature bearing on this point have 

 been brought to light by Dr. Sternberg, in the following 

 experimentation, which I quote : 



" If we add a small quantity of a culture-fluid containing 

 the bacteria of putrefaction to the blood of an animal, with- 

 drawn from the circulation into a proper receptacle, and 

 maintained in a culture-oven at blood heat, we will find that 

 these bacteria multiply abundantly, and evidence of putre- 

 factive decomposition will soon be perceived. But if we 

 inject a like quantity of the culture-fluid with its containing 

 bacteria into the circulation of a living animal, not only docs 

 no increase and no putrefactive change occur, but the bacteria 

 introduced quickly disappear, and at the end of an hour or 

 two the most careful microscopical observation will not reveal 

 the presence of a single bacterium. This difference we ascribe 

 to the vital properties of the fluid as contained in the vessels 

 of a living animal; and it seems probable that the little 

 masses of protoplasm, known as white-blood corpuscles, are 

 the essential histological elements of the fluid, so far as any 

 manifestation of vitality is concerned. 



The writer has elsewhere suggested that the disappearance 

 of the bacteria from the circulation, in the experiment above 

 referred to, may be effected by the white corpuscles, which, it 

 is well-known, pick up, after the manner of amoeba?, any par- 

 ticles, organic or inorganic, which come in their way. And 

 it requires no great stretch of credulity to believe that they 

 may, like an amoeba, digest and assimilate the protoplasm of 



