'202 ANIMAL HKAT. 



bottle is 52 cubic inches, and in the calculations after the ex- 

 periments, two cubic inches have been allowed for the air con- 

 tained in the different tubes, and for the small remains of air 

 in the bladder after being nearly emptied by pressure. 



% 



Mode of using the apparatus. 



Use of the In order to ascertain the quantity of air consumed under 



apparatus .in ordinary circumstances, the animal was placed on the stand 



which 3n <ini- 



mal was in- under the bell-glass, the bladder being emptied by pressure, 



closed, and the an d the gum-bottle being distended with atmospheric air. 



air a terwards _. . . ' . . ,. . 



examined. During the experiment, by pressing occasionally on the gum- 

 bottle, the air was forced from it into the bell-glass. On re- 

 moving the pressure, the gum-bottle became filled by its own 

 elasticity with air from the bell-glass. Thus the air was kept 

 in a state of agitation, and the dilatation of the bladder pre- 

 vented the air being forced through the quicksilver under the 

 edge of the bell-glass. At the end of the experiment, the 

 gum -bottle was completely emptied by pressure, and allowed 

 u ,.:, to be again filled with air from the bell-glass : this was repeated 

 two or three times, and the air in the bottle was then preserved 

 for examination. The proportion of carbonic acid being as- 

 certained, and the capacities of the different parts of the appa- 

 ratus, and the space occupied by the animal being known, the 

 total quantity of carbonic acid formed, and consequently of 

 oxigen consumed, was easily estimated. 



Artificial res- When the experiment was made on an animal in whom 



piration con- the functions of the brain were destroyed, and in whom, there - 



ducted after * , . , ' . 



the functions * or ^j voluntary respiration had ceased, the narrow extremity 



of the brain of the tube was inserted into an artificial opening in the tra- 

 e $ t y "chea, and the animal being placed under the bell-glass, the 



lungs were inflated at regular intervals, by means of pressure 

 made op the gum-bottle. The tube being smaller than the 

 trachea, the greater portion of the air in expiration escaped by 

 the side of the tube into the general cavity of the bell-glass, 

 while the gum-bottle filled itself by its own elasticity with 

 air through the opening G. At the end of the experiment, 

 a portion of air was preserved for examination, and the quan- 

 tity of carbonic acid was estimated in the way already de- 

 scribed. 

 t> The" 



