150 CONTAGIOUS DISEASES. 



the rim of the glottis is considerably swollen, and the tonsils 

 much enlarged. Emphysema of the lungs is very commonly 

 met with, and is a condition which causes great distress to the 

 animal prior to its death. The remarks of Dr. Sanderson upon 

 this point are very interesting. He says, " During the first stages 

 of the disease respiration is performed in a perfectly natural 

 manner, but about the fifth day irregularities begin to be 

 observable. From time to time the rhythmical movements of 

 the chest are interrupted, and expiration is accompanied by an 

 audible moan. On the sixth day (that is, in fatal cases, the day 

 before death) the breathing usually assumes a character which 

 IS so remarkable that if once observed it cannot be forgotten. 

 The chest dilates suddenly, but apparently with considerable 

 effort, in consequence of, as I believe, the unnatural permanent 

 expansion of the lungs due to obstructed expiration. This 

 inspiratory movement is immediately followed by closure of the 

 glottis, the expiratory muscles being at the same time thrown 

 into violent action, much in the same way as they are in the 

 act of rumination. The closure of the glottis is always attended 

 with a sound (such as might be produced by the sudden closure 

 of a soft leather valve) so loud that it can be heard at a con- 

 siderable distance. This sound coincides with the resisted 

 expulsive effort, which is often so strong as to throw the whole 

 body of the animal into oscillation. The chink of the glottis is 

 continuously closed for one and a half to two and a half seconds, 

 the chest remaining expanded and motionless. At the end of 

 this period the air shut up in the thoracic cavity is expelled 

 with a peculiar grunting noise, which is quite as characteristic 

 as the valvular sound already described. It is immediately 

 followed by a renewed inspiratory effort." Dr. Sanderson says 

 that this peculiarity of movement is the cause of the interlobular 

 emphj'-sema. He says, " The pause, instead of occurring between 

 each expiration and the succeeding inspiration — that is, when the 

 breathing apparatus is in a state of relaxation — occurs when the 

 chest is expanded, or, more accurately speaking, in the middle 

 of the expiratory act ; for, inasmuch as the expulsion of air from 

 the chest commences immediately after the chest is filled, a 

 considerable quantity escapes before the glottis has had time 

 to close. At the moment that closure takes place the air con- 

 fined in the chest is strongly compressed by the action of the 



