76 



THE NATURE OF ANIMAL LIGHT 



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

 as the prothoracic light organs of Pyrophorus, or scat- 

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



MT 



Fio. 24. — DiBtal portion of malpighian tubule 

 of Bolitophilat 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. 



