LUMINOUS ORGANS 



739 



Figs. 887 and 888. — Panceri's Representation of a Comb -Jelly. 



Fig. 887, 



Fig. 888. 



^ Fig. 887 bj' clay ; Fig. 888 by night (E. X. Harvey's Living Light, Princeton 



University Press). 



were melted and consumed by heat,"" wrote Charles Darwin of the '" burning 

 of the sea " as he sailed in the Beagle off the coast of Brazil, " without 

 being reminded of ]\Iilton"s description of the regions of Chaos and Anarchy." 

 Among the higher animals, numerous Coelenterates show this activity — 

 many hydroid polyps and jellyfisli (particularly Pelagia noctUuca which 

 forms a striking object in the Mediterranean at night) and possibly all the 

 delicate freely-swimming Ctenophores (comb-jellies), luminescing usually 

 over their entire surface when stimulated (Figs. 887-8). The brittle-stars 

 (Ophiuroiclea) contain the only luminescent representative of the Echino- 

 derms. Among worms, luminescence is restricted to some species of terres- 

 trial Oligochsetes and marine Polychsetes when they are irritated, while 

 only one nemertean worm {Empledonema kandai) has been described which 

 luminesces when it is touched or stretched (Kanda, 1939). The marine 

 worm, Chcetopterus, which lies in a tube buried in the sand, forms a very 

 striking picture indeed (compare Fig. 896). 



Figs. 889 and 890. — The Beetle, Phesgodes 



Fig. 889. 



Fig. 890. 



Fig. 



889 the beetle by day ; Fig. 890 the beetle photograpliecl in its own light 

 (E. X. Harvey's Living Light). 



