CAUSES OF DISEASE. 19 



formation of such districts, the grasses, no matter how abundant 

 they might be in quantity, are defective in some constituents, and 

 calculated rather to induce disease than support life, until such 

 grasses have attained a certain age, coincident with the period of 

 the blossoming of the white clover. 



In soils deficient in certain mineral constituents, the plants 

 grown thereon will also be deficient in those, if not artificially 

 supphed ; as, for example, as stated by Mr. Fleming, there is no 

 phosphate of lime in the soil of the alluvial tracts on the banks 

 of the Eliiue. What is necessary for the growths of plants is 

 derived from the atmosphere, which supplies no less than 400 

 grammes to each hectare, according to Burrell, and which is depo- 

 sited by the rain. In dry years, however, this supply fails, and 

 the plants are then deficient in this most essential ingredient. 

 The consequence is, that the creatures which consume these plants 

 siiffer more or less, and this is now recognised as one of the causes 

 of that special affection of the bones of animals in those regions 

 which has received the name of Osteoclasty. 



It is well known in Scotland that certain nervous diseases, 

 more particularly that known as " louping-ill " in lambs, are 

 only witnessed in certain localities, — very often the breadth 

 of a river being sufficient to separate the unhealthy from the 

 healthy groand. Many sheep-farmers and shepherds have long 

 believed, what is now demonstrated to be the case, that " louping- 

 ill " is only seen upon land infested with ticks, and that ticks 

 are the cause of the disease ; while it is possible to have land 

 infested with ticks, and yet have the sheep free from louping- 

 ill, as all ticks do not seem to contain disease germs, and it is 

 clearly proved that louping-ill is not seen where ticks are 

 absent. — (See " Louping-Ill.") 



The influence of marshes and undrained lands in predisposing 

 to and exciting disease is well known, and need but be merely 

 referred to here. Such. diseases as rheumatism, dysentery, and 

 typhoid diseases in animals, and intermittent fevers in man, 

 are traced to the influences — malarial — of such lands. It is now 

 demonstrated that anthrax diseases are due to a specific germ^ 

 the Bacillus anthracis, and that they cannot be developed except 

 by the introduction of the germs into the animal body. The 

 subject will be discussed hereafter: at the present, I have only 

 to state that moist lands have a great influence on the develop- 

 ment of anthrax, and tliat since this country has been to a 



