402 THE POPULAR SCIENCE MONTHLY 



their chemical composition and to a certain extent in their physiological 

 action. The ptomaines have sometimes been called the animal alka- 

 loids. This, however, is misleading, as ptomianes may be formed in 

 vegetable as well as in animal proteins. Their essential difference is 

 to be found in their origin. The ptomaines are decomposition prod- 

 ucts and largely belong to the aliphatic series, whilst the true plant 

 alkaloids are cyclic compounds and practically all of them pyridin deri- 

 vatives. Owing to the wide variation in the chemical constitution of the 

 ptomaines no analytical methods are known or possible by which they 

 can be differentiated as a class from the vegetable alkaloids. This is 

 possible in the case of certain ptomaines but not all. As a result 

 of this it is not difficult to see how serious medico-legal problems may 

 arise. It is believed in not a few instances ptomaines have been mis- 

 taken for the vegetable alkaloids in chemico-legal analyses. 



For our knowledge concerning the ptomaines we are indebted very 

 largely to the investigations of Selmi, Nencki, Gautier and Brieger. 

 Selmi was the first (1874-77) to suggest the name — ptomaine — and in 

 fact the first to announce their true nature and origin. Nencki was the 

 first (1876) to isolate a ptomaine (collidine) in pure form and deter- 

 mine its chemical formula. Gautier has given the best classification of 

 both the ptomaines and leucomaines. To Brieger, however, belongs the 

 credit of isolating the largest number (nearly one half) of the known 

 ptomaines and of giving us the best methods for their determination. 

 Vaughan and Novy in this country have made some valuable researches 

 along this line. As the result of an investigation of a number of cases 

 of cheese poisoning they succeeded in isolating a substance which when 

 administered to animals produced symptoms quite similar to those 

 caused in the human subject by the poisonous cheese. To this they gave 

 the name tyrotoxicon. This poison or one very similar has also been 

 isolated from ice cream and mill<:. The chemical composition of tyro- 

 toxicon has not as yet been definitely determined. 



In foods like cheese and certain sausages which depend for their 

 flavor on the action of certain microorganisms it is not strange that we 

 should at times have the formation of poisonous compounds. The so- 

 called process of " ripening " as applied to food products is in fact a 

 partial putrefaction in which we have as the result of bacterial action 

 the formation of ammonia compounds and amino acids which render 

 the food more palatable. It is therefore not a matter of surprise that 

 we should have at times a condition of " over-ripening " with the 

 formation of chemical compounds of a poisonous character. It is to be 

 borne in mind that ptomaines are not found only as the result of 

 advanced putrefaction. Bather are they the products of the earlier 

 stages of protein decomposition. In advanced putrefaction they may 

 themselves be broken down into more simple compounds. Thus 



