re See ee ea 
a en ee ee a oe ee Ee eee eel el ee ee CS EE T S 
1892.) Comparative Physiology of Respiration. 827 
mal remained in the jar the more nearly normal would be 
the respiratory changes; the experiments were, therefore, con- 
tinued only so long (one or two hours) as was found necessa 
to produce sufficient change in the air and the dissolved gases 
of the water to render the analysis unmistakable. 
Proceeding with the method just described the results given 
in the following table were obtained: 
Table of mixed respiration showing the number of cubic centi- 
meters of oxygen removed from air und water, and the amount of 
carbon dioxide added to the air and the water. 
Oxygen. Carbon Dioxide. 
o 
From From To 
air. water. air. § water. 
Ganoid fish (Amia calva) . . 65 10 22 53 
Tadpoles (Larval batrachia) . 70 5 24 51 
Soft-shelled turtle (Amyda 
WRU) os. a oS e a: o. 10 29 
Bull frog (Rana catesbiana) . 183 4 110 77 
It requires but a glance at the figures in this table to see 
that the aerial differs markedly from the aquatic part of the 
respiration. Even in the frog, in which the skin forms the 
only aquatic respiratory organ, the tendency is marked. The 
law appears to be unmistakably this, viz., that in combined 
aquatic and aerial respiration the aerial part 18 man ly for the 
supply of oxygen and the aquatic part largely for the excretion of 
carbon dioxide. This law, which I stated in 1886 (8), has been 
3The oxygen from both the water and the air and the carbon dioxide in the air 
were determined with exactness in all the experiments; but owing to the failure of 
some steps in the titration for the carbon dioxide in the water, the figures given for 
the Amia and the soft-shelled turtle are the calculated results, assuming that the 
respiratory quotient is one, as that is the relation found by analysis in the other cases. 
This table will be greatly extended when the results of the investigation now in pro- 
gress are published. 
