PATHOGENIC BACTERIA 253 



the majority of the heavy metals. On account of their marked 

 lability, chemical analyses cannot be made with accuracy. It 

 is possible that as physical chemistry is developed, more in- 

 formation will be gained in regard to these substances. In- 

 vestigations are being carried on at the present time by some 

 of the noted physical chemists. Many facts have been learned 

 about toxins by means of animal experimentation. 



It is, however, established that toxins are not true proteins 

 as they give none of the reactions for these substances. They 

 seem to be more closely related in their various reactions to 

 the enzymes. For example, it is impossible to isolate them 

 pure, and they are not like proteins but seem like enzymes to 

 be collodial substances of high molecular composition. Both 

 toxins and enzymes pass through porcelain filters, but have 

 their strength much reduced. They rarely pass a dialyzing 

 membrane. They are both destroyed by 80 C. moist heat, 

 but will withstand 100 C. dry heat and low temperatures 

 for some time. They rapidly deteriorate on standing, and this 

 seems to be due to the destruction of one part of the enzyme 

 or toxin molecule. The toxin and enzyme molecules are 

 made up of two distinct chemical parts or groups. One 

 part combines with the substance attacked (haptophore), and 

 the other portion produces the toxic or fermentive effects and 

 the destruction of the substance (toxophore or zymophore 

 group). 



The part of the toxin or enzyme molecule which is affected 

 by the various agents is the toxophore or zymophore group, 



