310 AGRICULTURAL AND INDUSTRIAL BACTERIOLOGY 



the skin frequently they find conditions favorable for devel- 

 opment. They have optimum moisture, optimum food con- 

 ditions and optimum temperature for their rapid growth. 

 They can be stopped only by specific defensive devices on 

 the part of the body. As a result of their growth and of the 

 irritation of tissues due to the resultant injury, the blood 

 capillaries expand and become engorged. Serum is poured 

 out into the tissues and passes into the wound. This serum 

 ordinarily contains antibodies, particularly opsonins. As a 

 result of the union of opsonin with the bacteria, the white 

 blood cells are also attracted to the area involved. These 

 white blood cells have the power of leaving the blood stream, 

 passing out through the capillary walls, and soon come to 

 lie in great numbers around the injured area. They are 

 so tightly packed together in many cases that they consti- 

 tute what is termed a pyogenic membrane, capable in most 

 instances of effectually preventing further spread of the 

 microorganisms through the tissues. The opsonized bacteria 

 are then more or less rapidly destroyed by the white blood 

 corpuscles. The blood serum and the white blood cells 

 together with some bacteria and disintegrated tissue cells 

 constitute pus, and a wound producing pus is said to sup- 

 purate. Eventually the microoganisms are usually disposed 

 of and healing occurs as the result of the development of 

 new tissue. It is evident that suppuration is one manifesta- 

 tion of an inflammation. 



Nonspecific Inflammation. As noted above, many kinds 

 of bacteria are capable of producing inflammation. In 

 some cases these bacteria are capable of causing the so- 

 called specific diseases, such as the typhoid bacillus, the 

 pneumococcus (producing pneumonia), or the bacillus of 

 tuberculosis. In other cases inflammations are produced 

 by what are termed the nonspecific, pyogenic cocci, that is 

 microorganisms usually not responsible for the so-called 

 specific infectious diseases, but capable of causing a great 



