#46 CATTLE 



chemical affinity or attraction ; and the carbon which it contains is 

 attracted by the oxygen which abounds in the atmospheric air, and 

 is taken out of the circuhition, and passes off in breathing. Carbonic 

 acid gas, or fixed air, is formed by the union of the oxygen and the 

 carbon, the presence of which in undue quantities renders the air 

 destructive to hfe. The other constituents of the blo^ have also an 

 affinity for oxygen, and more of that gas is taken from the atmos- 

 pheric air, and passes through the membrane of the air-cells, and 

 mingles with the blood. 



The change, then, from venous to arterial blood consists in the car- 

 bon being taken away, and oxygen imbibed ; and this is effected by 

 the blood being brought so nearly into contact with atmospheric air, 

 of which oxygen is a constituent part, and which has a greater 

 affinity for carbon, and other principles in the blood, than it has for 

 the gases with which it was combine. ^ in the constitution of atmos- 

 pheric air. 



The capillary vessels, now carrying arterial instead of venous blood, 

 unite and form larger and yet larger vessels, until the united stream 

 is poured into the right cavity of the heart, thence to be propelled 

 through the frame. This subject has been treated at somewhat 

 greater length, because the lungs of the ox afford the best illustration 

 of the division of the bronchial tubes, and the separation of the sub- 

 stance of the lungs into distinct lobuli, or little lobes, in which the 

 bronchial tubes terminate, and the air-cells are developed. 



CATARRH, OR HOOSE. 



Anatomical detail may now, for a considerable time, be laid aside, 

 and inquiry be made into the diseases of the respiratory organs. 

 Those only of the first of the air- passages, that of the nose, have as 

 yet been considered ; however, inflammation spreads beyond the 

 lining membrane of the nasal cavities, and involves the fauces, the 

 glands of the throat, and the upper air-passages generally ; it is then 

 no longer coryza, but is catarrh, or better known by the term hoose. 

 This is a disease too little regarded in cattle, but the forerunner of 

 the most frequent and fatal diseases to which they are subject. 



It is often hard to say whence catarrh, or common cold, arises. 

 The slightest change of management or of temperature will some- 

 times produce it. In the beginning of spring, and towards the latter 

 part of autumn, it is particularly prevalent. Young beasts, and cows 

 after calving, are ve^y subject to it. In a great many cases, how- 

 ever, it is the result of mismanagement. When cattle are crowded 

 together, they are seldom witliout hoose. If the cow-house be heated 

 considerably above the temperature of the external air, it is sure 

 to be there. Many a sad cold is caught at the straw-yard, and 

 particularly by young cattle : the food is not sufficient to afford 



