PATHOGENIC BACTERIA 247 



(ia) As a result of damage nerve cells and 



fibers, secreting cells, vessel walls, or 

 (20) Changes of a reactive nature in the blood- 

 forming organs (Bones, spleen, etc.). 

 (b) General anatomical changes due to malnu- 

 trition or increased waste. 

 B. Changes in Metabolism. 



Occurrence of fever, errors of assimilation and 

 elimination. 



The effects of bacterial action in the body, briefly stated, 

 are as follows : (a) Degeneration and necrosis ; (b) regen- 

 eration, reactive and defensive changes. Degeneration and 

 necrosis are due to the susceptibility and vulnerability of the 

 tissues. In the latter process (b) in all probability the pha- 

 gocytes and the body fluids are both responsible. 



The position of the lesions in the body is not easily ex- 

 plained by any mechanical means. Without doubt the 

 microorganisms or their toxins and special varieties of tissue 

 cells enter into chemical combination with each other. There 

 is a selective action on the part of the bacteria or their toxins 

 for these special tissues. The affinity of the tetano-spasmin 

 of the tetanus toxin for nerve cells is a case in point. 



In acute infections by bacteria there is usually a locus of in- 

 flammation at the focus of the infection. Hemorrhage, oedema, 

 and in some cases suppuration may be attendant conditions. 



In chronic infections, as, for example, the infective granule- 



