76 



THE NATURE OF ANIMAL LIGHT 



that these may be single, as in the common fireflies, paired, 

 as the prothoracic light organs of Pyropliorus, or scat- 

 tered over the surface of the body, as in so many shrimps. 



Fio. 24. — Distal portion of malpighian tubule 

 of Bolitophila, showing modification to form pho- 

 togenic organ {after Wheeler and Williams) . MTi, 

 MTi, malpighian tubules forming photogenic 

 organ; R, reflector; M, muscle; T, trachea. 



cephalopods and fishes, when they are often called photo- 

 phores. The light cells proper are often associated with 

 reflectors, lenses, opaque screens and color screens. 



