LITERATURE FOR 1912 ON THE BEHAVIOR OF 

 SPIDERS AND INSECTS OTHER THAN ANTS 



C. H. TURNER 



Sumner High School, St. Louis, Mo. 



TROPISMS 



i. Thigmotropism. Wodsedalek (no) deposited a brick in a 

 vessel of water. On top of this brick he placed a few small 

 pebbles of different sizes. On these pebbles he balanced another 

 brick in such a manner as to form a graduated space between 

 the bricks. A large number of the nymphs of Heptagenia inter- 

 punctata Say were placed in the water. In a short time, all of 

 these may-fly nymphs were clinging, dorsal side downward, to 

 the under side of the uppermost brick. A stone, with several 

 attached nymphs, was placed in a tin vessel of water and the 

 temperature of the water gradually raised. When the tem- 

 perature had reached 42 ° C. the nymphs began to leave the 

 stone, and by the time it had reached 45 ° all had departed. 

 A stone so large that a portion of it would project above the 

 water, was placed in an aquarium in which a chunk of ice was 

 kept. In a short time all of the nymphs in the vessel were 

 clinging to the submerged portions of the stone. The stone was 

 then heated from above. As the stone gradually became hot, 

 one by one the insects let go ; but as soon as they were cool, 

 they returned to the stone. Occasionally one of these returning 

 nymphs would turn away just before reaching the stone, and 

 other nymphs leaped from point to point along the rock, as 

 though seeking a cooler place. Most of the nymphs spent their 

 time roaming back and forth between the hot stone and the 

 cool water. Wodsedalek noticed that, when given the oppor- 

 tunity, a nymph would wrap itself about a small pebble and 

 become so rigidly fixed in that position that moulting was im- 

 possible. These experiments and observations caused Wodse- 

 dalek to conclude that strong positive thigmotropism is the 

 most pronounced feature in the behavior of these may-fly nymplis'. 



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