142 Bureau of Farmers' Institutes. 



best food stuffs given in balanced rations, pure-bred animals, 

 everything first class and all under the keen observation of ex- 

 perts who note details and record them — yet somewhere in the 

 past a number of tuberculous animals were bought and added to 

 the herd. Those diseased animals looked all right, else they 

 would not have been purchased at high prices. And after a few 

 years we find that 25 to 50 per cent, of the herd is tuberculous. 

 Remember that cattle stand in rows in many cases. The manger 

 is a continuous trough. The partitions between animals are low 

 and the cattle can reach each other on either side. They can 

 cough up and blow sputum to a considerable distance, where it 

 may fall on cattle to be licked off, or on food, or in water, or in 

 feed troughs. The animals are turned out for exercise or pasture, 

 drink at one trough lick themselves and each other, and drool 

 upon litter or herbage that others eat. When confined in the 

 stable during winter, think how the dried sputum is converted 

 into dust and wafted about by the breath blown from the ani- 

 mals, by their getting up, lying down, shifting feet, switching 

 tails, the opening and shutting of doors, the sweeping, the gen- 

 eral stirring up at the time of foddering, and you will realiz*' 

 that there is a series of motions night and day always operating 

 to favor dissemination of the disease by ingestion, inhalation, and 

 direct contact with mucuous membranes. Suppose that we say 

 of 200 animals 80 are tuberculous; in this number are some with 

 disease so located as not to be harmful to others, but manv 

 are diseased in organs which allow free exit to the infectious 

 material. The attendants breathe this germ-laden atmosphere, 

 they handle the cattle, and no doubt often convey to their nostrils 

 and mouths sputum from the cattle. They and their families, 

 and the proprietors and their families drink the milk, eat the 

 cream, butter and cheese, if the last is made, and in some cases, 

 though not often, they eat the flesh of calves or older animals. 

 Here, then, is the greatest abundance of infective material — in- 

 halation of germs before breakfast; at breakfast they are spread 

 over the oatmeal, poured into the coffee, on the fruit, spread on 

 the bread, taken in the glass of milk. All day the air is rich 



