TOXINS 25 



remain within the bacterial cells and are only liberated upon their 

 death and disintegration, the endotoxins. Closely related to the 

 second class are the so-called toxic bacterial proteins or plasmins. 

 These do not separate from the structures since bacteria which 

 produce them furnish a toxic mass if thoroughly washed, ground 

 and rewashed. ^ 



Examples and Characters. [Soluble or Extracellular Toxins. The 

 best examples are those of the tetanus and diphtheria bacillus. In 

 diseases caused by these germs, bacteria do not enter the body fluids 

 but the general manifestations are due to absorbed soluble poisons. 

 Such toxins are soluble in water; they are rendered inert by heating, 

 sunlight and some chemicals. They dialyze very slowly and are not 

 crystallizable. They may be precipitated with the albumen frac- 

 tion of the medium. They may be precipitated and dried in which 

 state they keep much longer than when in solution, and then are 

 more resistant to heat. Curiously enough the toxins may be de- 

 stroyed by proteolytic enzymesTj Some toxins are complex; the 

 tetanus toxin for example, contains two elements, one a dissolving 

 power on red blood cells, the other a stimulator of the motor 

 system. J5 ocouJil* / 



f^Endotoxins. These are exemplified by the poisons of the typhoid 

 and plague organisms. We know little of their chemistry but we 

 may assume that it is of protein material and similar to that of the 

 bacterial cell. These toxins are less rigidly specific than the extra- 

 cellular poisons. They are probably quite complex in activity as 

 they give rise to various anti-poisons when in the animal body. 

 These poisons are resistant to heating at 80 C. and keep under 

 artificial conditions much longer than soluble toxinsj 

 jTjihe toxic bacterial proteins are best exemplified by tuberculin. 

 This is a complex mixture of the proximal principles of the tubercle 

 bacill us and is probably albuminose in character. These substances 

 are almost as specific for their own germs as the toxins and much 

 more so than the endotoxins. They are capable of producing a 

 reaction in animals similar to that which might be produced by the 



