36 INFECTION 



Toxic. Characterized by restricted growth and toxin dissemi- 

 nation. 



Septic. Characterized by unrestricted growth in the blood and 

 lymph. In the three groups, the damage is done ultimately, by 

 metabolic products acting on the tissues. If the product is not 

 soluble the harm done is purely local, as in the formation of tubercles 

 by the toxin of the tubercle bacilli. 



If the growth is restricted, as in tetanus and diphtheria, the toxin 

 being soluble and diffusible, harm is done to tissues remote from 

 the infected area. 



Anthrax and streptococci and other pus organisms by rapid 

 increase in the blood eventually infect all the tissues. 



Combinations of these forms of infection may be at first confined 

 to some particular area like the pneumococcus, which are generally 

 restricted to the lungs at the outset, but ultimately they infect the 

 blood, causing septicaemia and localized lesions in more or less 

 remote parts, such as the veins of the leg, or inflammation of the 

 meninges. 



Soluble products of bacterial activity which are alkaloidal (basic), 

 crystalline in character, and mostly poisonous, are known as pto- 

 maines, or putrefaction alkaloids. They are highly complex in 

 chemical structure, and are difficult to isolate. 



Certain albuminoid bodies, products of bacterial activity, known 

 as toxins, are produced by several pathogenic bacteria. 



Those that are essentially bound up in the protoplasm of the 

 bacteria itself, are known as intracellular toxins, and bacteria plas- 

 mins. The tubercle bacillus, and other members of the acid-fast 

 group, the colon and typhoid bacillus, and the cholera spirillum all 

 contain these. They may be extracted by freezing the organism 

 with liquid air, and grinding it while frozen and brittle, or by simply 

 grinding it with sterile sand and water. The new T.R. tuberculin 

 belongs to this group of toxins. 



Bacterioprotein or plasmins are albuminous bodies produced 

 by bacteria that are not altered by heat, and which produce fever 



