380 



COMPARATIVE PHYSIOLOGY. 



on expiration ; though the latter act reminds us of the pro- 

 longation of the ventricular systole after the blood is expelled. 



10 



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Fie. 305.— Tracings of reBpiratoiy movements of indivi^nals belonging to different 

 groups of tlie animal kingdom (after Thanhofler). Differences in depth, frequency, 

 and especially regularity, are very noticeable. 1, fish; 8, tortoise; 3, adder (in 

 winter); 4, boa-constrictor (in summer); 5, frog; 6, alligator; 7, lizard; 8, canary- 

 bird; 9, adult dog; 10, rabbit: 11, man; 12, dog: 13, horse. Compare these, and 

 note that in nl respiration is shallow, and in ml deep. 



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