508 CHAINS OF CIRCUMSTANCE 



face of Europe, harassing and devastating the great cities, 

 until none were left fit to bury the dead. This infectious 

 and air-borne pneumonic plague is a possible successor of 

 the rat-carried bubonic plague, so that the Great Plagues 

 may well be examples of the recoil upon man's own health 

 of his influence in spreading the Black and the Brown Rats. 



Although the danger of great outbreaks in this country 

 seems to have largely disappeared, it is well to remember 

 that in Britain there have been epidemics of plague so 

 recently as 1900 and 1910, and that the disease is almost 

 constantly present in the great seaports of the world. So 

 effective is commerce in its distribution that tjie epidemic 

 which started in China in 1894 had by 1908 afflicted 51 

 different countries and had been carried to all the continents 

 of the world. 



But the rat is a source of further mischief: it is the chief 

 medium whereby the Round Worm (Trichinella spiralis] 

 infects pigs, whence it reaches man through the eating of 

 improperly cooked pork. So widely spread and so serious- 

 for man is the resulting disease of trichinosis, due to the 

 lodging of the parasite in muscle or intestine, that most 

 civilized countries have been compelled to institute strict 

 inspections for the detection of infected pork. And rats 

 besides are mechanical distributors of all the ugly con- 

 taminations of the sewers typhoid fever, scarlet fever, 

 diphtheria and many more; for the sewer and the drain 

 are the rat's main thoroughfares. 



Fortunately, however, man's influence upon the animal 

 world has not always recoiled upon his own head in new 

 and fell diseases. 



AGUE IN SCOTLAND 



Of the ailments which laid hold of our forebears a couple 

 of centuries ago, none was more prevalent or more persistent 

 in its attacks and effects than the Ague. Especially in the 

 spring-time, when trying conditions of weather and reduced 

 physical fitness due to bad housing and poor food and clothing, 

 paved the way for relapses, the ague passed through Scotland 

 like a blight. Contemporary references to the disease show 

 that it prevailed in particular amongst the labouring classes, 

 so that in many districts it was with difficulty that the heavy 



