Lung Plague and OTiolera. 157 



quantity of this morbid quality of blood. This increase 

 of carbonaceous and animal poisons in the blood thickens 

 it, making its circulation more slow and difficult than is 

 natural or healthy. 



The animal- matter expired by breathing, is stated on 

 good authority to be an " active and dangerous poison." * 

 It seems that two hundred out of three hundred .soldiers 

 were poisoned in a few hours, by breathing over such ex- 

 pired poison, in a cavern they were confined in, after the 

 battle of Austerlitz. And so poisonous is carbonic acid 

 known to be, that formerly suicides poisoned themselves by 

 inhaling carbonic acid, set free by burning charcoal near 

 the floor, in close unventilated rooms. The poisonous nature 

 of retained excretions is, however, now so well understood 

 that the danger of inhaling such matter is fully recognized, 

 as to the human subject, and — let us add — as to horses also, 

 as the latter have plenty of exercise and breathing. 



The blood becomes more loaded with excretory poison- 

 ous matter from every reduction of oxygen, carbonic acid 

 taking the place that oxygen should occupy. 



As cows become larger producers of milk, they are 

 usually more closely confined, many of then: breathing 

 over expired air that contains excretory poisons, in consid- 

 erable quantity. And this increase of excretory matter in 

 the blood continues, until at length the blood becomes so 

 overloaded with these poisonous matters that it irritates, 

 and thus weakens the membranes of the lungs. The lungs 

 are the natural outlet of this poison, being traversed by 

 this morbid blood in vast quantity, therefore the lungs are 

 more liable to iritation and injury by poisoned blood than 

 any other organ. 



To show the danger which cows that are confined in 

 badly ventilated stables, and over-fat hogs that huddle to- 

 gether in crowds, are exposed to, in breathing over any 



* See Hutchinson's Phyai., p. 136 to 140. 



