THE EADIATING ORGANS OF THE DEEP SEA FISHES. 189 



proxinifil mass which Leuckart terms " Glaskiirper," and which corresponds 

 to the inner region, is composed of Uirge crystal-clear radial cones similar to 

 cells; Leuckart, however, does not consider them as such, not having been 

 able to find a nucleus in them. Each organ is supplied by a slender nerve. 

 Leuckart considers these organs as accessory eyes, " Nebenaugen." It is 

 noteworthy that in the discussion following tlie reading of this paper Clans 

 (Leuckart, '64. p. 155) drew attention to the similarity between these organs 

 and the well-known structures of Euphausia, which were at that time also 

 considered as accessory eyes. 



Ussow (79, pp. 04-97, Plate 1, Figs. 1, 2, Plate 4, Figs. 2'), 26) has also 

 described the structure of the compound radiating organs of C. sJoaiii. He 

 finds them composed of two semispherical parts, the outer one of which is 

 occupied by a gelatinous mass, colorless and transparent in the living fish, 

 but coagulating and becoming opaque on being treated with the reagents 

 used for preserving the specimen. Below this gelatinous mass a mushroom- 

 shaped "lens" (79, Plate 2, Fig. 6 Kl) is seen, the cylindrical stalk 

 of which extends inwards, whilst the semispherical upper part, com- 

 posed of conic elements, protrudes into the outer gelatinous mass. This 

 " lens " appears to correspond to our middle region. The conic elements 

 of its distal, semispherical part are according to Ussow attenuated proxi- 

 nially to fine threads, which extend inward parallel to the axis of the organ 

 and form the stalk of the mushroom, in which tliey are connected with 

 granular multipolar cells. Concerning the itnier region Ussow merely 

 cori'oboi'ates the previous statements of Leuckart. These, however, he does 

 not seem C(n-rectly to have understood. Ussow also states tliat a slender 

 nerve leads to each organ. His description and also his figures are very 

 different from what subsequent authors have seen in these organs of C 

 sloani and show very little simihirity to the structure of these organs in 

 C. barbaius described above. 



Leydig ('79, pp. 3f)5-.382, Plate 15) examined the radiating organs of C. 

 sloani simultaneously with and independently of Ussow. His material, a 

 specimen preserved in spirits for several years, was not good, but nevertheless 

 his results were more valuable than those of Leuckart and Ussow. He also 

 chiefly studied the compound organs ; his notes on the others have been 

 referred to above. Tlio compound organs are surrounded by annular blood 

 vessels and a slender nerve branch leads to each. The distal portion of (he 

 compound organ is composed of two parts, an outer cap and a lower mass. 



