60 BOVINE PATHOLOGY 



Infection. Again, the air has an important influence on 

 respiration and cutaneous exhalations. When loaded 

 with deleterious gases it may act as a poison, but if these 

 be present only in small quantities it may simply produce 

 local disorder. Variations in the surrounding air consist 

 principally in moisture, temperature, or purity. When 

 moisture is deficient, but the air warm, the skin acts 

 readily but the muscular system is relaxed, hence the 

 system is predisposed to hernise. Tetanus is prevalent 

 in countries with such a prevailing climate as this, and 

 diseases become acute. Warmth, with moisture, while 

 determining blood to the skin, lessens the escape of 

 moisture from the surface and from the lungs ; thus a 

 sluggish lymphatic condition is induced, and the animal is 

 predisposed to dropsical effusions and low fevers. These 

 conditions are specially favorable to the growth and 

 multiplication of vegetable organisms, fungi, such as give 

 rise to anthracoid disorders and intermittent fevers. Cold, 

 with dryness, produces just the reverse effects, and gives 

 a very low rate of mortality. It is remarked that the 

 first touch of frost checks the ravages of an epi- 

 zootic. These conditions tend to slowness and stunted 

 growth, but produce hardihood, and are favorable to 

 the healing of wounds without the occurrence of septic 

 accidents. Cold with moisture, tends to a lowering of 

 vital energy, and an accumulation of impurities in the 

 system due to defective excretion by the lungs and skin, 

 diseases tend to an asthenic type, internal congestions 

 frequently occur, and rheumatismal diseases are prevalent 

 and severe. But where currents of air give rise to draughts 

 they are active agents in production of disorder, they 

 disturb the nervous system and originate inflammation 

 in that organ which is most predisposed to disease. 

 While warmth promotes fattening and the production of 

 milk, it must not be procured at the expense of venti- 

 lation and drainage. Unless fresh air is admitted, and 

 foul air escapes, and ejecta are not allowed to accumulate, 

 the air in the cowhouse will become overloaded with 

 impurities which predispose to disease, will tend to make 



