No. 530] THE PHOTOGENIC FUNCTION 



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The coloring and photogenicity of the organisms found 

 in the depths of the sea show some similarities to the 

 corresponding features of life on land. 



Take the family Buprestidee, of the genus Coleoptera, 

 of the order of insects. The insects of this family are 

 probably the most brilliantly colored of any of the beetles, 

 and are colored quite as brilliantly as the insects of any 

 other genus. The colors cover a quite wide range of 

 metallic, polished, glistening greens, blues, reds, coppery 

 and golden; many of the smaller species wear more 

 somber dark blues, browns and blacks, but as a class they 

 are brilliant and showy. Obviously, these colors would 

 be invisible in the absence of light, and need a light of 

 considerable intensity to bring out their full value. Now 

 we find that almost without exception these Coleoptera 

 are diurnal; they attain their maximum activity during 

 the brightest daylight, and fly but little at night. But one 

 species has been reported to be luminous, and unless this 

 report is pretty definitely confirmed there is grave reason 

 to doubt its authenticity. 



Now let us consider the Lampyridae : The beetles of this 

 family of almost eleven hundred species are in the great 

 majority of instances, luminous ; the non-luminous species 

 form a decided minority of the true Lampyridre. They 

 are also, in the great majority of cases, mainly nocturnal 

 in habit, hiding out of the sunlight during the day; those 

 species which are markedly diurmil in habit are also those 

 which are non-luminous, or in which the luminosity is 

 relatively slight. In coloration, they show none of the 

 bright metallic, showy colors of the Buprestidae; black, 

 gray. In-own and yellow-brown predominate, with occa- 

 sional red markings, yellow stripes and indistinct lines 

 and spots. In them, the photogenic function possesses at 

 least two definite significances: (1) it is an adjunct of the 

 sexual organism of the insect, rendered of value to them 

 by reason of their nocturnal habits, and (2) it has a pro- 

 tective value. In the larvae it might also be considered 

 to have an aggressive value, in attracting the snails, etc., 



