182 SHEEP DISEASES: 



Mouldy foods may be placed in the same category with the 

 foregoing, and by the light of our greater knowledge of the 

 action of fungi in the system we are warranted in attributing 

 many of the diseases marked by a depraved condition of the 

 blood to their influence. 



Most certainly many moulds are active agents in the produc- 

 tion of inflammation of the mucous membrane of the bowels, 

 and they probably also in some instances cause abortion. 



With impure foods we may class infipure water — a prolific 

 source of morbid conditions marked by depravity of the blood, 

 and by diarrhoea and dysentery. 



Indirect Predisposing and Exciting Causes of Disease. 



Having glanced over direct, we may now with profit consider 

 those indirect influences which act as predisposing or exciting 

 causes to the development of disease, and one of the most import- 

 aot of these is the management of the land and of feeding. 

 Seeing that the growth of animals and vegetables moves in a 

 circle, and that both derive their nourishment primarily from the 

 earth, it follows that the earth must contain, in order for their 

 vigorous growth, all the elements they require and that those 

 elements must bear, as I have already remarked in reference to 

 the blood, a certain definite proportion to each other. 



Now it is quite clear that if the stockowner year by year 

 takes from the laud the important constituents of all organic 

 growth by putting animals thereon and allowing them to 

 devour the vegetable products and then devouring the animals 

 himself or selling them for some one else to devour, the land 

 must ultimately become impoverished : he cannot eat his cake, 

 and have it too. 



It may be held that much of the material taken from the 

 land is returned again to it in the shape of urine and dung, but, 

 allowing that this is so, what about the yearly deficit produced 

 by the removal of immense quantities of material in the shape 

 of mutton, blood, horn, skin, wool, &c. ? Then it may be said 

 that the air and the rain supply vegetables with nitrogen and 

 carbon. Granted, again, that this is so, what proportion of 

 soluble matter, especially on hillsides, is washed out of the soil 

 by rain ? 



The heather may be burned but by doing so much of its 

 nutrient matter is dissipated in the form of gas which is largely 

 carried away by the wind and benefits the neighbouring fields ; 

 or, if in close proximity to the sea, the fishes mayhap. 

 Certainly the ash of heather contains a small quantity of potash 

 and other salts which are thus restored to the grass, that is all 

 however — no nitrogen, no carbon. It would, I know, be simply 

 absurd on my part to tell the stockowner, as I have heard of 



