BACTERIAL POISONS. 1 63 



of the comparative facility with which they could be isolated in 

 a condition of purity, where their exact chemical nature could 

 be determined. They were found to be basic compounds 

 derived from nitrogenous material. 



A group of substances of a similar nature called leucomaines 

 has been discovered, which are formed within the body by 

 faulty metabolism, and not by the action of the bacteria. 



Further study has demonstrated, however, that the char- 

 acteristic features of the infectious diseases are not due to 

 ptomaines, but to certain poisonous bodies to which the name 

 toxin has been applied. Toxins have not been obtained yet 

 in a pure state, and consequentially their exact chemical char- 

 acter has not been determined; but much has been learned in 

 regard to their physiological action, and more information in 

 this direction is constantly being obtained by experiments. 

 They have very marked characteristics and they do not act like 

 ordinary poisons, but behave as if they had the power of 

 reproduction. An ordinary poison, such as arsenic, strychnia 

 and the like, begins to act as soon as it is absorbed — there is 

 no period of incubation. The toxins, on the contrary, have a 

 distinct period of incubation. If an animal is given a fatal 

 dose of arsenic or strychnia, it succumbs within a comparatively 

 short time; it is at most a matter of a few hours. But if an 

 animal is injected with a fatal dose of the toxin of tetanus it 

 takes some time, often several days, before any symptoms 

 develop, and moreover the animal may remain alive for days 

 afterward. In some respects the toxins resemble the physio- 

 logical ferments, ptyaline, pepsin and the like; but they differ 

 from these in that the physiological ferments are not themselves 

 used up in the process of fermentation, whereas the toxins 

 are used up in the production of disease. After starch has been 

 converted into sugar by ptyaline the ptyaline may be recovered 

 and used over and over again to convert more starch; but after 

 tetanus toxin has produced tetanus in an animal it has become 



