312 THE VOYAGE OF H.M.S. CHALLENGER. 



of 0'2 and a height of 0'06 mm., appearing perfectly stnictureless, and being formed of 

 a solid unMainable ydloiv substance, which may perhaps be a secretion poured into tliese 

 spaces. 



The fibrous tissue which separates the lenticular yellow bodies from each other 

 consists chiefly of slender spindle-shaped elements, with oval, highly stainable nuclei. 

 There seems to exist a very fine cuticular membrane surrounding each of the lenticular 

 1 todies. 



The volume of the tiluons tissue is about as great as that of the yellow substance iu 

 the lenticular bodies. 



(7) The meandn/orm gland-tubes. 



At the sides of the slime-canal (PI. LXXIII. fig. 55, h) large aud conspicuous highly 

 stainable glands (PI. LXXIII. fig. 59), which consist of meandriform tubes of circular trans- 

 verse section and uniform width, are met with. These gland-tubes, which do not appear 

 to open into the slime-canal, are completely filled with round cells each of which has a 

 very distinct cell-wall, a small nucleus, and transparent hyaline contents. They are very 

 similar to the short oval or cylindrical elements, with circular transverse section, which 

 are found in the slime-canal (PI. LXXIII. fig. 58). 



c. Innervation. 



I have mentioned above that 1 look upon the granular cells iu the slime-canui as 

 ganglion-cells. They are connected by a fine plexus, which extends up along the scales 

 and supplies the fibrous tissue between the leilticular bodies with nerves. A large bundle 

 of nerve-fibres, similar to that observed in other cases, is found in these organs in 

 Halosaurus, in the canal leading from the chamber through the scale into the 

 phosphorescent organ. 



d. Function. 



According to F. E. Schulze,^ the slime-canal is to be regarded as a sense-organ, 

 adapted to perceive vibrations of the water with wave lengths too great to be jtor- 

 ceptible by the car. In other words the slime-canal is a supplement to the ear, and 

 any further development of it should, one would think, be organs of sense of a similar 

 kind. In the abysses of the sea, whei'c Ught is scanty, this organ would be ])artieularly 

 valuable and so we might assume that here we have a case before us, where the slinit- 

 (xvnal sense-organ has been further developed aud complicated. 



The peculiar whitish colour of the organ and the light refiecting membrane which 

 clothes the chambers might, on the other hand, lead one to assume that these organs really 



' Loc. rit. 



