178 SHEEP DISEASES: 



with excessive quantities of nitrate of soda. Diabetes, if un- 

 checked, kills by exhaustion * 



The spleen (melt) and the lymphatic glands (kernels) are also of 

 great importance to animals for by them the white cells of the 

 blood are manufactvired, and in certain diseases the quantity of 

 Avhite cells becomes so excessive as to far outnumber the red 

 cells constituting " white cell blood " (leucocytosis) and produc- 

 ing emaciation and death. The spleen is influenced injuriously 

 by fever poisons and by the organisms of " anthrax," in which 

 disease it is often the first organ to become affected. The spleen 

 probably serves other purposes than that of manufacturing white 

 cells ; as iron, soda, and phosphates, with various extractive 

 matters, are found in tolerable quantity in its ash when it is 

 burned. 



Tlie lungs are of the greatest possible importance to life and 

 any interference with their function exercises an injurious influ- 

 ence upon the whole of the system and more particularly on 

 the blood and the brain, as it is through their agency that 

 carbonic acid is got rid of from the blood and oxygen supplied 

 to it ; or, in other words, it is in the lungs that the change from 

 venous to arterial blood takes place. Watery vapour too is 

 exhaled by the lungs, and probably, to some extent, volatile 

 matters also. Interference "vvith the excretion of carbonic acid 

 by the lungs tends to produce plasticity of the blood and favours 

 congestive processes. 



The sJdn, though last to be considered, is not the least in 

 importance particularly to the sheep. 



From this structure, under ordinary circumstances, watery 

 vapour is constantly being exhaled, constituting insensible per- 

 sinration; and in the event of any derangement of the kidneys 

 it takes on, if allowed to do so, compensatory action and assists 

 in getting rid of the excess of water from the blood. Not only 

 does it give off water, but it also, under certain conditions, 

 absorbs water ; that it possesses this function is sho^vn by the 

 fact that if an animal is placed in a bath and retained there 

 for a time, it gains in weight. 



Warmth favours the evaporation of moisture, cold retards or 

 arrests it ; and this is a matter of great importance to the sheep 

 because when its fleece, as so often happens, is saturated with 

 water and the weather is cold the skin cannot perspire ; on the 

 contrary water is absorbed and this is often aggravated by the 

 watery nature of the food, and by inactivity, from disease, of 

 the kidneys, and dropsy results. 



The facts just noted account for a further fact, viz., that while 



* During the last winter the author has frequently detected degeneration of the 

 kidneys in the carcasses of sheep which had suffered from water hraxy. He 

 pointed out this condition in similar cases many years ago. 



