SENSE ORGANS OF AMIURUS. 259 



papillary spaces, varies according to the part of skin where the 

 tumour is attached. On the lips, for instance, where there are no 

 clavate cells, the interpapillary spaces are chiefly occupied by spindle- 

 shaped cells, but elsewhere, where clavate cells occur, these also are 

 proliferated, being found in regular nests such as are represented in 

 Fig. 3. Everything indicates rapid division, but no further peculi- 

 arity has attracted my attention nor can I furnish any explanation of 

 the appearance of these, no doubt, pathological growths. 



CUTANEOUS SENSE ORGANS. 



Within recent years important contributions to the knowledge of 

 the sense organs lodged in the skin of Teleosts have appeared. Fol" 

 lowing up his earlier researches Leydig 1 has recently described those 

 of Esox, Gasterosteus, Acerina ;md Lota. Solger 2 has studied the 

 organs of the lateral line in various forms, and Bodenstein 3 has given 

 a careful description of those of Cottus gobio. 



I have not had access to Merkel's work 4 in which 5 a sharp distinc- 

 tion is drawn between two classes of cutaneous sense organs. Those 

 which he terms ' End-knospen.' (end-buds), the ' beaker-shaped 

 sense-organs ' of Leydig, are lodged on papillee of the cutis, and, 

 although freely distributed over the skin and in the mouth cavity of 

 Teleosts, are only found in the latter situation in higher vertebrata, 

 where they reappear as taste-bulbs. To the second class belong the 

 end-organs of the nerves, which are distributed to the lateral line and 

 the ' mucous ' canals of the head. Merkel terms this second class 

 ' Nerve nhiigel,' (nerve-hillocks), and points out their tendency to 

 withdraw themselves for protection from the surface of the integu- 

 ment within more or less completely closed canals, although, primi- 

 tively, all nerve-hillocks are free and exposed to the surrounding 

 medium (except for a protecting tube of cuticular origin), and in some 

 species such ' free-organs ' are alone present. The end-buds, on 

 the other hand, are always flush with the surface, certain of the ele- 

 ments even projecting beyond it, and indeed may be carried beyond 

 the general level of the integument where tactile sensibility is at its 

 highest development, as in the Kentucky blind-fish (Amblyopsis) , 

 the Indian Cyprinoids recently described by Leydig, and, in fact, in 



1 1. c. p. 22, et seq. * Arch. mik. Anat. XVIII., 384. 3 Zeit. wiss. Zool. XXXVII,, 121. 



* " Ueber die Endigungen der sensiblen Nerven in der Haut der Wirbelthiere." 



* Vide Wiedersheim Lehv. der vergl. Anat. S. :-i- r ,s. 



