490 THE AMERICAN NATURALIST [Vol. LIII 



more promptly than was the case when they were placed 

 on the ground with their heads directed away from 

 the water. All the gerrids reached the water— as was 

 generally the case in many other experiments of a simi- 

 lar character— with but a limited number of random 

 movements. The only prominent exception to this was 

 the gerrid used in Experiment XXXIV/ Usually, there 

 were one or two individuals that displayed this lack of 

 promptness. All the gerrids employed in the six experi- 

 ments consumed a total amount of time of 2 minutes 

 and 40 seconds. The average amount of time necessary 

 to return to the pool was 26f seconds. If Experiment 

 XXXIV should be omitted, it is evident that the total 

 amount of time consumed by five water-striders in reach- 

 ing the pool was 1 minute and 10 seconds. The omission 

 of this experiment reduces the average time, consumed in 

 reaching the water, to fourteen seconds. These results 



TABLE IV 



riMF Consumed b\ Water Stridfrs in Ef\ciii\g ^^ \ter from Distvnce 

 OF 1 Yard 



XXX. . . . 



xxxi 



XXXIII 



xxxiv 



XXXV 



are sho^v^l in I al.l. I\ Hi. miIu ,,t etlh i . \\n m 

 ments of a siiiiilar cliai'aclci- arc indK-alcd iii TaMc \ 

 and Table VI. 



5. Ep^pon^es WJiPii P<nnlh ' II :lh r<,ni S,,in, . \\n i i- 

 ments were performed with watcr-sl ndci-s liaviim' llie 

 long axis of the bodv |iarali«'l with the iiiaruin of the 

 pool. In all other respects, the conditions were sinidar 



