210 THE HUMAN SPECIES 



Sheep and goat .... 12-20 

 Dog .... . 15-28 



Cat 20-30 



Rabbit ...... 50-60 



Whale . . . . . .4-5 



Man ...... 12-19 



The intensity of the respiratory process, calculated on the 

 basis O-intake per kilogramme and hour, shows the following 

 marked variations in the different species of animal : 

 Frog O-intake per kilogm. and hour 0^07 gm. 



Horse 0-35 



Man 0-42 ,, 



Sheep 0-49 ,, 



Ox 0-55 



Cat roi 



Cockchafer ,, ,, ro2 



Dog 1-19 



Hen rig ,, 



Small song bird ,, i r64 



Pfliiger gives the following table of the respiratory quotient, 

 i.e., the relative volume of expired CO 2 to inspired O : 

 Herbivora 0*90- ro 



Carnivora O'75-O'S 



Man (omnivora) O'82 (average) 



When a man breathes deeply, the depth is proportionate to 

 the increase in the transverse and antero-posterior diameters of 

 the chest at the expense of the longitudinal. 



The average circumference at the height of the ensiform 

 cartilage, measured when resting, is in men 82 cm., in women 

 76 cm. (see Fig. 109) ; extreme inspiration increases the 

 measurement by about 8 and 7 cm. respectively. 



The inspiratory and expiratory capacity can be determined 

 with the spirometer. The vital capacity, i.e., the maximum 

 volume of air which can be inspired and expired at a single 

 breath, averages in men 3,700 c.c. and in women a trifle less. 



The vagus (tenth) nerve serves in man and animals as the 

 motor and sensory nerve of respiration. The laryngeal branch 



1 Munk-Schultz, he. cit., pp. 111-13, footnote. 



