52 C. H. TURNER. 



4:15 P.M., when I stopped for the day, none of the blinded 

 whirligigs had reached the water. Two had become lost in the 

 grass. Eight were still in the tray. 



These experiments show conclusively that the nearest body of 

 water exerts a directive influence upon the movements of the 

 whirligig beetle and that the control is exerted by means of 

 stimulus received through the eyes. 



CONCLUSIONS 



i . The checkerboard plate consists of a smooth board covered 

 with white oilcloth which is subdivided, by printed lines, into 

 one-inch squares. There is a leveling device by means of which 

 it can be made perfectly horizontal. Considering the center of 

 the board the center of a circle, the board is divided into eight 

 sections, each forty-five degrees wide. Starting at the middle 

 of one side the tips of these dividing lines are numbered from o to 

 315. This nomenclature makes it possible to arrange the speci- 

 men at the center of the board, with its head pointing in a certain 

 definite direction. When in use, by means of an adjustable 

 screen, the board is protected from the direct rays of the sun. It 

 is washed from time to time to free it from odors that may in- 

 fluence movements. Thus manipulated all possibility of geotac- 

 tic, chemotactic, and thigmotactic responses are eliminated; 

 hence this device forms an excellent means of investigating the 

 influence of bodies of water upon the behavior of small animals. 



1. It may be used in studying any walking land insect, milliped, 

 centiped, crustacean, or annelid. 



2. It may be used in studying flying insects that also walk; 

 but, in some cases it may be necessary to clip the wings. 



3. It may be used in investigating the behavior of many fresh- 

 water invertebrates (small snails, amphipods, isopods, crayfish, 

 some backswimmers, giant water bugs, water-striders, larvae of 

 straight-winged flies, dragonfly larvae, scavenger beetles, diving 

 beetles, whirligig beetles) ; in some cases it cannot be used be- 

 cause the animals cannot remain out of water long enough 

 (damsel-fly larvae); in yet others it cannot be used because the 

 creatures are too awkward when out of the water (large snails, 

 water-tigers). 



