XIII 



RESPIRATORY RHYTHM 



4'.):! 



they exhibit an increment and decrement (Fig. 230) : at other 

 times an increment alone (Fig. 230) ; at others a decrement alone 

 (Fig. 231) ; at others again the respirations of the group all exhibit 

 much the same intensity. 



B 



FIG 



. 229. Periodic respiration observed in man at high altitudes. (Mosso.) A, Tracing obtaini-ii 

 with Marey's pneumograph on Mosso himself when awake, at 3(>20 metivs. 15, Tracing taken 

 during light sleep from watchman at the Regina Margherita hut, 4500 m. 



Periodic respiration is not essentially a morbid phenomenon. 

 It invariably accompanies the lethargy of hibernating animals 

 (Mosso, Fano, Langendorff, Patrizi) ; is sometimes seen in the sleep 



FIG. '230. Periodic respiration in man. (A. D. Waller.) The rotating cylinder moves slowly. 



The signal marks minutes on abscissa. 



of healthy individuals, particularly in old people and children 

 (Mosso) ; often at high altitudes (2500-4500 m. above sea-level) ; 

 it is observed conspicuously in sleep (Fig. 231), and in a less degree 

 in waking (Egli-Sinclair, Mosso). 



A number of attempts have been made to evoke experimental 



