THE PEST OF RATS 25 



parasite are the rat and the hog itself. Pork 

 becomes trichinous, then, only when swine eat 

 the flesh of infected rats or hogs. Country 

 slaughter-houses, where rats are abundant and 

 swine are fed on offal, are the chief sources of 

 trichinous pork. That the danger from this 

 source has not been confined to the rural 

 slaughtering-places alone, is shown by the in- 

 vestigation conducted by the Biological Survey 

 in 1909 into the "rat-nuisance," said to exist 

 about the great packing-houses in Chicago and 

 St. Louis. The older establishments were 

 found to be infested with rats, causing a se- 

 rious aggregate loss, and endangering both the 

 health of the workmen and the wholesomeness 

 of the product; but this state of things has 

 been greatly improved, and new buildings are 

 designed to be rat-proof. 



Rats creep through drains and step about 

 in all sorts of filth; and to their feet and fur 

 clings slime which may be loaded with germs 

 of typhoid, diptheria and any other of the 

 malignant list of diseases due to bacilli that 

 develop in darkness and filth. Consequently 



