172 EXPEEIMENTS OF REGNAULT AND EEISET. 





4th. In fowls, submitted to their usual diet of grain, there is often 

 Respiration more oxygen in the carbonic acid disengaged than was furnished 

 of birds. j n f nc a i r }^y respiration. The surplus of course comes from 

 the food. 



5th. The quantity of oxygen consumed in a given time varies with 

 f the state of digestion, motion, and other circumstances. Com- 

 motion, age, pared together, the consumption is greater among the young 

 than among adults, greater among those that are lean but in 

 good health than among those that are fat. 



6th. If we take an equal weight of the animals under examination, the 

 influence of quantity of oxygen varies much with their absolute size ; 

 the size of ani- thus it is ten times greater among little birds, such as spar- 

 rows and green-finches, than among common fowls. This 

 is owing to the fact that, since these different species have the same tem- 

 perature, and the little ones present relatively a greater surface to the 

 ambient air, they must consume relatively more oxygen to keep up their 

 heat to the standard degree. 



7th. Hibernating animals, such as marmots, when perfectly awake, ex- 

 Res iration of ^ibit no peculiarity, but when fast asleep often absorb nitro- 

 hibemating gen. The ratio of the oxygen contained in the carbonic acid 

 to that inspired is very low, scarcely amounting to 0.4, the 

 missing oxygen escaping in the compounds of the urinary secretion ; 

 but since this removal takes place only periodically, the sleeping marmot 

 exhibits the remarkable phenomenon of increasing in weight by respira- 

 tion alone. 



8th. The consumption of oxygen by sleeping marmots is very small, 

 scarcely -^ of what they require when awake. At the moment they 

 awaken from their lethargy, their respiration becomes extremely active, 

 and during the period of their awakening they consume much more oxy- 

 gen than when they are completely awake. Their temperature rises rap- 

 idly, and their members gradually lose their stiffened state. While tor- 

 pid they can remain without difficulty in an atmosphere which would 

 suffocate them in a few moments if awake. 



9th. Cold-blooded animals, for an equal weight, consume much less 

 Res iration of ox yg en * nan hot-blooded. Frogs with their lungs cut out 

 cold-blooded continue to breathe with nearly the same activity as before, 

 often living for several days, the proportions of the gases 

 absorbed and disengaged differing little from what is observed in the 

 case of uninjured frogs. This shows that their respiration can be con- 

 ducted by the skin. The respiration of earthworms is the same as that 

 of frogs, as regards the quantity of oxygen consumed, when they are com- 

 pared under an equal weight. 



10th. The respiration of insects, such as May-bugs and silk-worms, 



