SECRETION AND ABSORPTION OF GAS, ETC. 125 



Biot's Analyses of Gas from the Air-Bladder. 



By Johannes Muller and other physiologists this gas 

 was spoken of as a secretion, but ideas about secretion 

 were then still in their infancy. Muller, it is true, possessed 

 what appears to be the right idea, that all true secretion 

 is, in the most intimate sense, a " vital process," and that 

 therefore the problem of the cause of secretion directly in- 

 volves the whole question of the cause of life itself. This 

 idea of Miiller's was, however, for the time lost sight of 

 in the course of the movement towards physico-chemical 

 speculation which overwhelmed physiology about the 

 middle of the present century. 



Biot draws attention to the fact (evident from the 

 table of his analyses) that the greater the depth at which 

 a fish is caught the higher the percentage of oxygen in 

 its air-bladder. Moreau confirms this ; and his experi- 

 ments throw further light on the subject. He found 

 that if the air-bladder was artificially emptied, either by 

 puncture or by reduction of atmospheric pressure, the gas 

 which is afterwards gradually secreted into the bladder is 

 richer in oxygen than before, and usually far richer in 



1 Often caught at 3000 feet. 



