402 C. H. TURNER 



C. F. Curtis Riley (79) is convinced that dragon-fly nymphs 

 are positively thigmotactic and that this causes them to collect 

 in groups. 



W. P. Gee (32) claims that the young of the scale insect 

 Lecanium quercifex Fitch are pronouncedly positively thigmo- 

 tactic. A young nymph was placed upon its back and an un- 

 hatched egg applied to its upstretched feet. The insect at once 

 began to juggle the egg and continued to do so for nearly thirty 

 hours. The egg hatched at the proper time; but the young 

 insect had a hard time escaping from the grasp of the juggling 

 scale. 



2. Phototropism. Mast (57) states that the male fireflies 

 studied by him always turned so as to face the glow of the 

 female and then moved directly towards it.* He also noticed 

 that the male continued to move in the direction of the glow 

 even after it had ceased. Mast thinks the following mechanical 

 explanation is justifiable. "It we assume * * * that there 

 is in the male a specific response for the illumination of every 

 surface of the eye; that is, that momentary illumination of the 

 posterior surface is followed by a turning through 180 and then 

 locomotion straight forward, the side of the eye by turning 

 through 90 ° and then forward movement, the front of the eye 

 by a torward movement alone, etc., it is not difficult to con- 

 ceive all of these reactions to be purely mechanical reactions of 

 the nature of unconscious reflexes." However, Mast does not 

 consider these orientations tropisms in the sense of Loeb; for 

 he writes: "Here we have a case in which it is clearly demon- 

 strated that light does not act continuously in the process of 

 orientation as demanded by Loeb's theories, a case in which it 

 is also clearly demonstrated that a continuous action of the 

 stimulating agent is not necessary to keep the organism oriented." 



C. H. Turner (100) confined several of the mason wasps, 

 Trypoxylon albotarsus, in wire cages and experimented on them 

 with narrow bands of light, broad bands of light and cones of 

 light. In some experiments direct sunlight and in others the 

 beam of an electric projecting lantern served as the illuminant. 

 Red, orange, blue and colorless lights were used. "As a rule, 

 under the influence of a strong white light, these wasps would 

 make active flights oi else walk rapidly about." "When a light 



* See Mast, under " Mating." 



