Catarrhal Bronchitis. 207 



diffusion is always going on through imperfectly closed hatches, 

 companion ways, and ventilators, yet, that these are often insuflE- 

 cient has been amply shown by such losses as are reported above, 

 as well as by the bronchitis and tuberculosis which Drs. Whitney, 

 Lyman, and Williams have found in the lungs of American ani- 

 mals arriving in England. ' ' 



"organic matter in expired air." 



' ' The decomposing organic matter given off by the lungs and 

 skin is probably the most injurious of -the animal excreta, when 

 allowed to act on the system for a length of time. This exhaled 

 organic matter is easily recognized in the air by chemical tests, or 

 by the putrid odor evolved when cotton wool, that has been 

 breathed through, is left to soak in otherwise pure water at a 

 temperature of 70° to 80° Fahrenheit. The experiments of Gav- 

 arret and Hammond, in which expired air had its carbonic acid 

 and water vapor removed, leaving only the organic matter, showed 

 that the latter was highly deleterious. Hammond found that a 

 mouse died in forty-five minutes in such an atmosphere. It has 

 also been again and again demonstrated that air containing a 

 given amount of carbonic acid as the result of respiration is far 

 more poisonous than air which contains the same amount of car- 

 bonic acid as a product of combustion." 



' ' water vapor in expired air. ' ' 



' ' The amount of water vapor given off by the lungs varies 

 greatly according as the air is already more or less saturated with 

 water. As the air in the stalls between decks is always saturated 

 with water vapor, we may take the very lowest estimate for each 

 animal, namely, 60 ounces in 24 hours, which for a cargo of 200 

 head would amount to over 93 gallons. And this is in addition 

 to the exhalations from the skin and the bowel and kidney excre- 

 tions. The air between decks is therefore constantly saturated 

 with moisture which condenses and runs down in streams on 

 every solid object. Among the ill effects of this saturation may 

 be noted :" 



' ' First. The saturation of the air with water vapor increases 

 the exhalation of carbon dioxide from the lungs. This effect on 



