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THE AMERICAN NATURALIST [Vol. LIII 



the hemipterons in any manner that would be effective in 

 producing definite responses to the source of this mois- 

 ture, as for example positive responses, resulting in the 

 water- striders wandering toward the pool. This is the 

 more improbable when it is recalled that the gerrids were 

 ten yards away from the water, and in other instances, 

 not recorded in detail in this paper, they were even far- 

 ther away than this, eleven, twelve and fourteen yards 

 distant. I also have observed their responses in the dry 

 bed of a stream, when there were pools of water at a less 

 distance than ten yards apart.. 



i]i this con7ieclion it may be of interest to quote a state- 

 ment from Weiss (1914, p. 33): 



"Wiiiolf- forms of (ierris marginalus, which is quite common through- 

 out New .lei'sey, when removed from a pond containing some three 

 thou«nid scjuare feet of water and liberated at distances of one, two, 

 tlu'ee. four. live. six. seven, eight, and nine yards from the water, imme- 

 diately made their way l)ack to the water without hesitancy. Of course 



When liberated at n distance of ten yanls. they had some slight trouble 

 in getting tlieir !)eariii.i:s. but after n'laking several false starts, finally 

 wound uj) by going in the direct if>n of the water. At a distance of 



be-fore the rioht direction was located. At thirty and forty yards away, 

 they seemed to lo^e their bearings completely and moved aindesslv about 

 in all directions. Kven at the end of an hour thoy were no nearer the 



The observations of Weiss were of responses of water- 

 striders under exjK^rimental conditions and not observa- 

 tions of their res]-)onses under the natural conditions of 

 their own environment undisturlied })y any extraneous 

 -timulu-. a< was the ca^e of my observations. However, 

 it is pcrtiiKMil to (liivct jUtciition to certain facts in con- 

 lu'clinii uith hi^ .AiH'iimcnt^. It is evident that the re- 

 sjxdi-.- nUii i r'is ninrfiiudt us, especially those individuals 



