EXAMINATION OF POISONOUS FOODS. 227 



quite general use to designate illness due to infected food. While it 

 is true that basic substances of bacterial origin constitute in some 

 instances the actual materies morbi, this is not always, or even gen- 

 erally, the case. Among the poisonous bacterial products there are 

 many that are not basic, and many others concerning the chemical 

 nature of which we are yet very much in ignorance. In a large 

 proportion of the instances we are ignorant not only of the chemistry 

 of the poisons which induce the untoward effects, but of the bacteria 

 through the activity of which these poisons are generated. More- 

 over, we cannot in cases of bromatotoxismus draw a sharp line of 

 distinction between intoxication and infection. Food poisoning may 

 originate in either of the following ways : (1) The food is infected 

 and the poison is generated only and wholly before the food is 

 taken. (2) The infecting organism may begin the elaboration of its 

 poisonous products outside of and continue the same process inside 

 the body. (3) The infection may not result in the production of 

 poisons until the food is taken into the body. In all of these forms, 

 infection of the food is the essential element ; it is this that must be 

 prevented, and to this especial attention must be called. 



How shall we proceed in the examination of food suspected of 

 having caused sickness or death ? 



In the first place, the possibility of the ill effects having been due 

 to metallic poisons should be considered. In cases in which this 

 possibility exists such poisons should be sought by methods given by 

 the best toxicologists, and of which it is not the purpose of this book 

 to speak. In case the substance to be examined consists of canned 

 food the tests for mineral poisons should always be made. How- 

 ever, when a teaspoonful of ice cream causes nausea and vomiting, 

 the idea that these effects can be due to sulphate of zinc dissolved in 

 the freezer is too preposterous and absurd to be worthy of serious 

 consideration by anyone familiar with the quantity of this salt neces- 

 sary to act as an emetic. 



If there be a sufficient quantity of the food a portion of it should 

 be fed to animals. As a rule, the best animals for experiments of 

 this kind are puppies and kittens. It should be remembered that 

 rabbits and guinea-pigs cannot vomit and we have learned by experi- 

 ments that guinea-pigs fed exclusively upon pure milk die ; they are 

 not able to digest the casein which forms hard balls in the small in- 

 testines and mushy masses in the large intestines, and the animals 

 succumb within eight or ten days, apparently from intestinal ob- 

 struction. If they be fed upon hay or other vegetable food along 

 with the milk, they are apparently able to digest the casein. How- 

 ever, under no circumstances are they fit animals for experimenta- 

 tion, when the purpose is to determine whether or not milk or any 

 of its products is poisonous. 



A thorough examination of foods for bacterial poisons cannot be 



