PTOMAINES 529 
recently the conception that foods may cause infection has crept in 
and this is being confirmed. Specific bacteria are now being recognized 
as the principal factors in many cases. In others, the toxins produced 
by bacteria are ingested and these produce intoxications. 
Certain characteristics of food infection or poisoning have pre- 
vented rapid advances in our knowledge. The occurrence of a small 
number of cases in a family is investigated with some difficulty because 
these individuals often are engaged in quite different activities. Much 
easier is 1t to study the problem when the individuals are members of 
units whose activities are much alike. Consequently some of the most 
valuable data with regard to food poisoning has been collected from 
prisons, barracks and similar groups. Probably, in the smaller units, 
cases of food poisoning have been overlooked and attributed to other 
causes. Then, in the past, many cases of food poisoning have been 
reported, the study of which included no bacteriological or chemical 
examination. 
The causes of food poisoning are varied because there is little agree- 
ment with regard to a definition for the term ‘“ poison,’’ which is a 
difficult term to define. However, for convenience, the following 
causes of food poisoning may be mentioned: 
I. Ingestion of foods containing pathogenic bacteria. 
II. Ingestion of foods containing poisonous products of bacterial 
katabolism—toxins. 
III. Ingestion of foods which are naturally poisonous, such as mush- 
rooms. Certain alkaloids are present. 
IV. Ingestion of foods containing poisonous metals. 
Ptomaines. These are toxic amines and, as indicated in the chapter 
on intestinal bacteria, they are the products of bacterial action. They 
are basic in character and have been called ‘‘ animal alkaloids.” Most 
of them do not contain oxygen; the following are typical ptomaines: 
(CHs)NHoe. .. 0... ce eee e es methylamin 
(CHz)gNH. ok ec ence ene eas dimethylamin 
(CHa)gN.. ete ec een en eens trimethylamin 
NHe—CH»e—CH2—CH2—CHe—NH2.... 2.2... 2028. putrescine 
NHe—CHe—CH»s—CH2—CH»—-CH2—_-N Ho see ew eee cadaverine 
Not all of the ptomaines are poisonous. The more elementary amino 
compounds are probably not poisonous. The ptomaines do not hold the 
position in food poisoning as formerly. Their importance in the past 
probably originated in their isolation from bacterial cultures and the 
