170 THE INDUCTIONS OF BIOLOGY. 



from prolonged abstinence. Even fish, though much more 

 active than most other aquatic creatures, appear to undergo 

 but little loss of substance when kept unfed during con- 

 siderable periods. Reptiles, too, maintaining no great 

 temperature, and passing their lives mostly in a state of 

 torpor, sujffer but little diminution of mass by waste. When, 

 however, we turn to those higher orders of animals which 

 are active and hot-blooded, we see that waste is rapid : 

 producing w^hen unchecked, a notable decrease in bulk 

 and weight, ending very shortly in death. Besides 



finding that waste is inconsiderable in creatures that pro- 

 duce but little insensible and sensible motion, and that it 

 becomes conspicuous in creatures that produce much insen- 

 sible and sensible motion ; we find that in the same crea- 

 tures there is most waste when most motion is generated. 

 This is clearly pro\ed by hybernating animals. ^' Va- 

 lentin found that the waking marmot excreted in the average 

 75 times more carbonic acid, and inhaled 41 times more 

 oxygen than the same animal in the most complete state of 

 hybernation. The stages between waking and most pro- 

 found hybernation yielded intermediate figures. A waking 

 hedgehog yielded about 20*5 times more carbonic acid, and 

 consumed 18*4 times more oxygen than one in the state of hy- 

 bernation." If we take these quantities of absorbed oxygen 

 and excreted carbonic acid, as indicating something like the 

 relative amounts of consumed organic substance, we see 

 that there is a striking contrast between the waste ac- 

 companying the ordinary state of activity, and the waste 

 accompanying complete quiescence and reduced temperature. 

 This difference is still more definitely shown by the fact, 

 that the mean daily loss from starvation in rabbits and 

 guinea-pigs, bears to that from hybernation, the proportion 

 of 18'3 : 1. Among men and domestic animals, the relation 

 between degree of waste and amount of expended force, 

 though one respecting which there is little doubt, is less 

 distinctly demonstrable ; since waste is not allowed to go on 



