266 



G. T. CALDWELL. 



covered with black paper and a small opening at one side per- 

 mitted of observation without disturbing the animal by the 

 movements involved in the manipulation of the apparatus. The 

 slugs usually came to rest in a short time in the darker region of 

 the chamber. Series of determinations were made until the 

 readings became constant. 



130 12.0 IH> 166 90 80 70 60 S9 

 Vfe/vAf /-Y /Hi //i Qtatas 



FIG. 4. The effect of desiccation on the carbon dioxide production of the slug. 

 Control curves indicated by letter (.4) and enlarged to twice the scale of experi- 

 mental curves. Total time of each experiment about 8 hours. 



The rate of carbon dioxide production increased with desic- 

 cation until there was a loss of water equivalent to from 20 to 30 

 per cent of the body weight when the rate fell below normal and 



