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THE AMERICAN NATURALIST [Vol. XLI 



the spouting occurred five times, while for the entire period of 

 three minutes there were, on the average, four spoutings per 

 minute. At the end of the three minutes the rate of respiration 

 was found to be 41 per minute. 



(2) Following is the record of another experiment. 

 10.00 A. M. A skate was removed from the water. 

 11.15 A. M. Feeble respiratory motions of gill chambers 

 and spiracles still in progress at the rate of 28 per minute. 

 The spiracle is continuously wide open, its anterior Hp 

 contracting very slightly at each expiratory movement. 

 The moutli is contiiiuously shut. 



11.20 A. M. The skate is put into well aerated sea water. 



11.21 A. INI. The spiracular action is stronger and weak 

 mouth action begins. 



11.25 A. M. The spiracle closes completely at each expira- 



These experiments, then, so far 

 conditions of gradual approach t( 

 is left in a small volume of unchn 

 increasing restlessness attended b^ 

 greater frequency of spouting, 

 there were, earlv in the experiinei 



