Epidemics. 13 



spread a morbific or depressing agency over man and 

 beast for a short period. 



therefore, for persistent epidemic disease, such as plague, 

 or cholera, volcanoes and earthquakes are of very secon- 

 dary importance. 



Upon the whole, temperature, moisture, and dead calms, 

 have far more to do with endemic disease than any mere 

 sudden eruption, or disturbance on the earth's surface ; but 

 for widespread epidemics something is wanted of a more 

 general nature, slower, but more constant in its opera- 

 tion. 



Leaving the conditions of epidemics, a few remarks may 

 be made as to the peculiarities of epidemic disease. 



The first and foremost of these is the power of isolation, 

 which is so singular in some epidemics. Although according 

 to an old proverb, " From the stall to the hall," is endorsed 

 the fact of ailments in cattle, of an epidemic character, 

 rarely existing for long, without spreading their baneful 

 influence to man. 



At times we have special diseases in poultry, and the 

 rest of the farmyard healthy. Game, of the feathered tribe, 

 in certain seasons will be diseased, vermin, as foxes, at 

 another time, hares more rarely, yet never simultaneously. 

 So, in blights and diseases affecting the vegetable kingdom, 

 such as of wheat or any special kind of the cereals. In 

 given years certain kinds of grubs or caterpillars will infest 

 almost every apple ranging over entire tracts of country. 



