DISEASES OF CATTLE 57 



Another disease of sheep that is conveyed in the same way, is the 

 nodular disease. It is due to a small worm, and while it does not 

 manifest itself until winter, the time the infection is spread from one 

 sheep to another is during the summer months. 



Such parasitic diseases as paper-skin, liver-fluke and lung worm 

 of sheep, and the worms in hogs, horses and cattle, are all conveyed 

 in much the same way and are largely due to surface water. Pure 

 water from deep wells is the prevention. 



VENTILATION OF STABLES. 



Abundance of sunlight and of fresh pure air is the basis of cure 

 that has been adopted at modern consumptive sanitariums'. The 

 prevalence of tuberculosis among both cattle and men is to a con- 

 siderable extent due to close confinement, for longer or shorter peri- 

 ods, in ill-ventilated and badly lighted rooms. Dark, close basement 

 stables for cattle, and tightly-bottled-up dwellings for men, women, 

 and children, are too often found in this and other countries. 



Ventilation is a mattter more of accident than of plan in most of 

 our houses and stables. As a consequence, the inmates are breathing 

 the same air over and over again. This would be bad enough if every 

 inmate of the house were perfectly healthy, for the products of respi- 

 ration, even of a healthy animal, are a mild poison, which are, how- 

 ever, prevented from doing much harm by being more or less diluted. 

 But when we remember not only that the expired breath of an un- 

 healthy animal contains the usual constituent of carbonic acid, but 

 that its presence is very likely to infect the air with the germs of dis- 

 ease as well, the necessity for frequently changing the air of occupied 

 rooms is quite apparent. 



In warm seasons, and in warm climates, the problem of ventila- 

 tion is a comparatively easy one. We have only to throw open our 

 dwellings to the action of the breeze, and the air is continuously 

 changed. But in the wintry season, and in rigorous climates, the 

 question is one of considerable complexity; for along with the de- 

 mand for fresh air comes another more immediately urgent the de- 

 mand for warmth. In cold weather, these two requirements must 

 necessarily conflict, and the one need is satisfied at the expense of the 

 other. That being the case, we manage to have the more urgent need 

 satisfied, and neglect the remoter necessity. We are more sensitive 

 to cold than to impure air ; and in order to secure a proper degree of 

 warmth without too great cost, we are content to ignore the fact that 

 we are breathing impurities. 



The question of ventilation involves the question of tempera- 

 ture. We have not only to make provision for bringing fresh air into 

 our dwellings, but we must warm it artificially after it is introduced. 

 Therefore, ventilation, particularly for dwellings, is doubly expen- 

 sive. We have to provide contrivances for renewing the air in houses 

 and stables. That is one item of expense. In stables we have to 

 guard against too great a reduction of temperature, and hence a sys- 

 tem of ventilation in stables requires either careful watching or spe- 

 cial appliances for warming the air. In houses, we generally expect 



