162 



LIGHT-ORGANS OF EUPHAUSIA. 



Clans * regards them as true accessory eyes. Sars,t 

 on the contrary, considers that they have no power of 

 sight, but are highly differentiated luminous organs. 

 He admits that they present a deceptive resemblance 

 to true eyes, but has convinced himself by observations- 

 of the living animal that they have no power of 

 vision. 



The fibrous fascicle (Fig. Ill,/) he finds to be the 

 chief light-producing part.t and the lens-like body in 

 front serves, as he supposes, for a condenser, producing 

 a bright flash of light, the direction of which the 

 animal, by means of its muscles, is able to control. 

 The anterior pair (Fig. 112, h), which differ some- 

 what in structure from the rest, are situated on the 



Y\g. ni.— Luminous organ of 

 Eiiphausia (alter Sars). /, 

 Fibres ; e, lens. 



Fig. 112.— Eye-stalk of Euphausia (after 

 Sars). lo. Luminous organ; a, lower 

 eye. 



eye-stalks, and appear to serve as " bull's-eyes " to 

 the true organs of vision. Sars considers that the 

 luminous organs do not serve as eyes, on the grounds 



* " Ueber einige Schizopoden und niedere Malacostraceen," Zeit. 

 fur Wiss. ZooU 1863. 



t "On the Scbizopoda," "Challenger Reports," vol. xiii. 



X Valentine and Cimningharo, in a memoir just published 

 (^Quarterly Journal of 3Iicroscopical Science, vol. xxviii.) deny this, and 

 attribute it to the inner surface of the reflector. 



