412 THE AJIEIUC AN NATURALIST [Vol. LIII 



have been described, were carried out, in which the heads 

 of the water-striders were directed away from the stream. 

 As before, a majority of the gerrids were successful in 

 reaching the water. The same distances were used as in 

 the former experiments, but in all cases there was less 

 promptness in moving toward the brook. It also was 

 evident that thoi'c wore more random movements than 

 was true in the ronnci- oxpcrinionts. Of the water- 

 striders phicr.l I'oiii' \;ii(ls ;i\v;i>- from the stream, a 

 greater ix'rccnt.-mv. tluin in ot' llie other experiments, 

 failed to rca.-li the w.-itrr. 



These iH'int.lM-..,!^ cinpl.-v ,m1 iwo motliods of locomo- 

 tion on hni(i, \v;ilkiiiu' ;i!i<l jmtiping. The more rapid 

 progn^ss w;is niixh' 1)>" Jiiiiiping. The individual jum])S 

 avcr.'i.ucd nlxuit one inch in length, although tmpiently 

 they wci-c ^rc.'itcf than this. Sometimes when jumping, 

 tlic u<M'i-iiI- m;i(l(' a coiiiplete turn, as if they were not 

 ahlc. t'lillv . t.. roiitrol the oi'iontation of the body, and this 

 frecpicntly rc-nltcd in chjinainu- their direction of prog- 

 ress. In \h'\< (MMincctifni. ! \\\>\\ lo direct attention to the 

 fact that l-NMMihMu- i VAh, y. W-u has observed a some- 



