ALKALOIDS. 407 



Ptomaines not only possess the general characters of true alka- 

 loids, bat even the often highly characteristic color-tests of the latter 

 are in some cases almost identical with those of ptomaines. Thus, 

 ptomaines have been found which resemble in their chemical 

 properties as well as in their physiological action upon the animal 

 system, the alkaloids morphine, atropine, strychnine, coniine, digi- 

 tal ine, etc. 



Many attempts have been made to find some characteristic prop- 

 erties by which to differentiate between the putrefactive and the 

 vegetable alkaloids, but practically without results. It is true that 

 most vegetable alkaloids are optically active, while ptomaines are 

 inactive, but it does not often happen that ptomaines are obtained in 

 such quantities as to permit of an exact determination of optical 

 properties. 



Under these conditions it is evident that the toxicologist has a most 

 difficult task, when called upon to examine a body (especially when 

 already in a state of decomposition) for alkaloidal poisons. How 

 many times, in former years, chemists may have unjustly claimed the 

 presence of poisonous vegetable alkaloids in material given them for 

 examination, we cannot say, but we do know of a number of cases 

 of recent date in which such claims were shown to be based upon 

 errors, made in consequence of the close analogy between ptomaines 

 and alkaloids. 



While the poisonous properties of some ptomaines are well marked, 

 others are more or less inert. The poisonous ptomaines are now 

 often termed toxines, in order to distinguish them from the inert 

 basic products of putrefactive changes. 



The toxines are of special interest to the physician, because it is 

 now assumed that infectious diseases are caused by the poisonous 

 products formed by the growth, multiplication, and degeneration of 

 micro-organisms in the living body. 



The great likelihood of this statement is of far-reaching impor- 

 tance, as it opens a new field for investigation in connection with the 

 treatment of infectious diseases. 



Non-poisonous ptomaines. A number of these basic substances 

 have been known for a long time. Some of them are also formed by 

 other processes than those of putrefaction, and the term ptomaines 

 may, therefore, not well be chosen for all of them. However, the 

 close relationship between these substances unites them into a natural 

 group, of which the following members may be mentioned : 



