320 BACTERIOLOGY. 



body-cells, and, although in somewhat slighter 

 degree, " active " tolerance of poisons, can per- 

 sist for months and even for years, because 

 these conditions do not depend upon the tran- 

 sient bacterial invasion, but upon the acquired 

 properties of the body-cells. The body-cells, 

 because of their relatively great independence 

 of varying conditions of nutrition, are able to 

 cling to their inherited or acquired character- 

 istics. For this reason they render more per- 

 manent the qualities of the blood and other 

 body-fluids which maintain an interchange of 

 substances with them. 



Without this intervention of the cells the 

 body-fluids very quickly rid themselves of 

 foreign substances either by excretion through 

 intestine, stomach, kidneys or skin, or by oxi- 

 dation or by chemical combination. New and 

 lasting characteristics are not acquired or pre- 

 served by the body-fluids alone. It is the organ- 

 ism of the host, the cellular tissue of the 

 human being, that reacts towards the stim- 

 ulus of those bacteria or bacterial proteids or 

 toxins with which we endeavor to heighten the 

 resistance towards parasites or parasitic poisons. 

 Bacteriology affords powerful support to cellu- 

 lar pathology, a fact that can not be urged too 

 strongly against Behring's view. 



In the case of " passive " vaccination, or the 



