670 RADIATION BIOLOGY 



out in this genus to remove prey must depend on optical cues. Heil 

 (1936) presented evidence indicating both form perception and good dis- 

 tance appreciation in jumping spiders. 



For insects Plateau (1885) held that reaction to light was entirely in 

 proportion to intensity and not toward the shape of areas providing the 

 light — this for the blowfly CaUiphora, the drone fly, and two butterflies. 

 Demoll (1913) and Baldus (1924, 1926), however, recorded fair form and 

 distance perception in dragonfly naiads. Baldus found in unilaterally 

 blinded specimens that binocular vision and size appreciation were both 

 important in controlling the snapping reaction toward prey. Verrier 

 (1929) noted that the leaf insect Phijllium had keen sight for moving 

 objects and that the male located the female visually. De Lepiney 

 (1928) found visual responses in caterpillars to vertical silhouettes, and 

 Hundertmark (1937a, c, 1938) used this technic extensively for evaluating 

 vision in these insect larvae. Goetz (1936), on the contrary, could 

 demonstrate no response to marks in caterpillars of several butterflies, 

 although larvae about to metamorphose were responsive to the general 

 direction from which light came. Sight responses in other insects indi- 

 cate many errors in behavior due to deficient vision, and false attempts 

 to mate arising from this difficulty. Von Buddenbrock (1935a,b) used 

 striped patterns to study form vision in the drone fly. 



A considerable literature has developed on the visual finding of mates 

 among the light-producing beetles known as "fireflies." Vision into the 

 red and infrared among such fireflies is a noteworthy fact (Buck, 1937) 

 in view of the spectral distribution of daylight. The only other infrared 

 response cited in the literature as being mediated through the compound 

 eye seems to be that of pigment migration in the ommatidia of the moth 

 Plusia (Kiesel, 1894). Spectral characteristics of pigment migrations 

 were studied in the visible by Collins and Machado (1935), with large 

 eff"ects reported in the ultraviolet but none in the infrared. Eltringham 

 (1923), using very different experimental technics, demonstrated that 

 different species of butterflies are quite unlike in their ability to see with 

 red light, and this ability seemed related to the colors in the insects 

 themselves. Other studies of pattern vision and form perception are 

 primarily those concerned with the honeybee, especially on conditioned 

 responses to marks placed outside the hive or in association with feed- 

 ing stations. Similar technics used with the wasp Philanthus have been 

 reported. Thus insects are not the reflex machines postulated by Loeb 

 and others. 



NOTE 



In the foregoing an attempt has been made to furnish a brief guide to 

 significant information on invertebrate photoreceptors. A digest of the 

 extensive and scattered literature is impossible in the space available; 



