ELEMENTAEY DEMONSTRATIONS 



147 



A mouse, owing to the greatness of its surface exposure in relation to 

 its mass, gives off 20 times as much C0 2 per kilo of body weight as a 

 man. The mass of a man is about 3000 times the mass of a mouse, but 



Fir,. 120. Zuntz respiration apparatus. The subject expires through the meter. 

 The inlet and outlet tubes are controlled by valves D and C, made of pieces 

 of intestine which have been soaked in glycerine. A small sample of the expired air 

 is steadily drawn off into the burette A by the escape of mercury from the tube 

 which is lowered by the revolution of the meter B. The meter gives the total volume 

 of air breathed. The measured sample in the burette is analysed by Haldane's gas 

 apparatus. 



the external surface of the man is probably only about 150 times that 

 of the mouse. A mouse weighing 25 grms. produces in one hour at 

 ordinary temperatures 0'25 grms. of C0 2 . A man weighing 70 kilos 

 produces 40 grms. in the same time. A mouse thus produces about 10 

 grms., and a man only J grm. per kilo of body weight. A mouse is 

 poisoned by CO in -^ the time of a man. 



When the Haldane-Pembrey apparatus is applied to a man, air is 

 drawn through the respiration chamber and the total volume measured 

 by a large meter. A small sample of the air entering and leaving 

 the chamber is drawn through two sets of absorption tubes for the 

 determination of the water and carbon dioxide and is then measured 



