xiii RESPIKATOBY RHYTHM 473 



found general acceptance, and Pfiiiger gave it the authority of his 

 name in 1868. 



A. Mosso was the first who, in 1885, pointed to some quite 

 evident facts which, according to him, show that " the number and 

 extent of the respiratory movements are not always in close relation 

 with the respiration of the tissues and the blood, while they are 

 directly proportional with the need for supply of oxygen or 

 elimination of carbonic acid." He gave the name of extra- or 

 luxus-respiration to the excess renewal of air in the lungs, such 

 as normally occurs and is not, strictly speaking, necessary to the 

 organism. 



Some of the facts which he brings forward do not really 

 appear to stand in close relation with the theory of luxus- 

 consumption. Such, e.g., are the well-known fact that respira- 

 tion is profoundly modified by simple nervous activity (emotions, 

 intellectual work) quite independent of the degree of venosity 

 of the blood; that dogs after running frequently pass from 

 deep respiration (dyspnoea) to quick and superficial breathing 

 (tachypnoea) as if the register were suddenly changed without 

 apparent reason ; again, that in sleep, both in man and other 

 animals, temporary disturbances of a purely nervous character 

 may be observed in the regularity of the rhythm. All these 

 effects confirm what we said above as to the influence exerted by 

 the nervous system upon the regulation, and more particularly 

 the mode of distribution of the work of the respiratory muscles, 

 and have nothing to do with the capacity for pulmonary ventila- 

 tion, which may continue practically unchanged in the time-unit 

 under very dissimilar and even opposite forms of respiratory 

 rhythm (Eosenthal). 



Another fact brought forward by Mosso is more significant, 

 i.e. that we can voluntarily reduce to about one-half the amount 

 of air inspired, without inconvenience, for a considerable period 

 (10-15 minutes). At the same time this would only bear on the 

 theory of luxus-respiration, if it could be proved that breathing, 

 when voluntarily restrained for so long a time, would not be 

 followed by a compensatory dyspnoea. 



Lastly, we attach great importance to the observations made 

 by Mosso during his Alpine excursions, which show that at a level 

 of 3000 metres much less air is breathed than at sea-level; 

 hence at sea-level the amount of air respired far exceeds the needs 

 of the organism. In proportion as one ascends, the superfluous or 

 luxus-respiration diminishes owing to the rarefaction of the air. 

 These high altitude effects do not, however, appear to be constant, 

 which as we shall see impairs their cogency for luxus-respiration 

 in the plains. 



According to Mosso, luxus-respiration (which we may shortly 

 designate eupnoea} is profitable to the organism, because it makes 



