110 VETERINARY STUDIES 



In some of our own work (Reynolds and Lipp) with a steer 

 closely confined in specially prepared tight stall, we obtained 

 the following record of CO, percentages after varying periods 

 of confinement. After 6 hours, .94 per cent; after 12 hours, 

 .71 per cent; average after two 24-hour periods, 1.03 per cent; 

 after 48 hours, .68 per cent. The animal was a young steer 

 weighing about 500 pounds, and was confined in a stall contain- 

 ing 784 cubic feet of air. 



Another steer 200 pounds heavier in the same series of experi- 

 ments gave for an average of three 24-hour periods, 1.09 per 

 cent; at 42 hours, .98 per cent. It may be interesting for the 

 student to note the decrease of CO2 rather than an increase, 

 which would usually be expected. This occurred many times in 

 our experimental work and is quite easily explained on chemi- 

 cal grounds. 



Necessity of ventilation. — To illustrate the effect of poor 

 sanitary conditions, particularly lack of ventilation, it is only 

 necessary to call attention to the common experience of moving 

 an animal affected with chronic glanders or tuberculosis from 

 a well-lighted and well-ventilated stable to one where the con- 

 ditions are the opposite. Under the latter conditions there 

 is often rapid development of a disease which had been 

 mild. 



Sick animals, especially those affected with respiratory diseases 

 — and this is true of many other diseases — need free ventilation. 



A warmly constructed barn in a cold climate is desirable if 

 sanitary conditions, such as abundant air, sunlight, good food, 

 and water, are provided. A good barn, with good ventilation, 

 should maintain a temperature above freezing even in very 

 cold weather. This means warm construction — number and kind 

 of animals taken into consideration. But making a barn warm 

 and tight may very easily establish an ideal place for the propa- 

 gation of germs, the spread of disease, and lowering of animal 

 vigor. 



Carbonic gas (CO,) can no longer be considered a reliable 

 index of an atmosphere's injurious quality. In fact, our work 

 has shown it to be a very unreliable guide in this respect. But 

 it is a convenient guide as to the amount of ventilation accom- 

 plished. 



Unventilated stable air. — Writers and teachers on the subject 

 of hygiene are agreed that unventilated air is harmful. The 



