110 BULLETIN OF THE 



Paris," VI., p. 332, in which he announces the discovery that the ducts 

 are organs of sense, carrying vibrations from the surrounding water to 

 tlie nerves. He also pointed out that these vessels could hardly be the 

 analogues of the batteries, both being found in the Torpedoes. Trevi- 

 ranus, Knox, and others followed, agreeing more or less completely with 

 his conclusions. Delle Chiaje, Savi, and other observers, still claimed 

 that the ducts were to be regarded as " organ i mucipari," distributing 

 the slime over the surface. 



Blainville, 1822, and others of his time and later, among them Miiller, 

 looked upon the canals as apparatus for the secretion of mucus. 



Savi, in 1840, announced his discovery of the " appareil folliculaire 

 nerveux " to the Scientific Congress at Florence, and a year later it was 

 published in the " Atti della tei'za Riuuione degli Scienziati Italiani in 

 Firenze." 



Mayer, 1843, arrived at conclusions similar to those of Geoffroy, 1802, 

 and held that the mucous ducts of the Raife were the analogues of the 

 electric batteries of the Torpedinidse. 



Savi, 1844, sent out his " Etudes anatomiques sur le Systems Xerveux 

 et sur rOrgane electrique de la Torpille," in Matteucci's work, " Traite 

 des Phenomenes Electro-physiologiques des Animaux," of which it forms 

 an appendix. Here he gives a detailed description and figures of series 

 of follicles on the Torpedo, which are apparently of the same character 

 as those sketched in the present work, on Disceus, Potamotrygon, and 

 Urolophus, and which are here proved to be part of the canal system. 



AVithout mentioning all the writers who may have touched upon, or 

 referred to either canals, follicles, or ducts, we may simply call attention 

 to Wagner, 1847, to whom is to be credited the hypothesis that the 

 function of the follicles of Savi is to excite the activity of the electric 

 organs, and then proceed to several of the more important contributions 

 toward an understanding of one or another of the organs. 



H. Miiller, 1851, makes three groups of the vessels, the greater part 

 of which are to him organs of sensation instead of secretion. To quote 

 his words, '• Unter der Rubrik ' Schleimkaniile ' sind bei den Knorpel- 

 fischen verschiedene gebilde zusammengefiisst, von denen nur ein Theil 

 den Schleimkanalen der Knochenfisch analog ist. Ein grosser Theil der 

 Kanale bei Knorpel- wie bei Knochenfischen hat bestimmt nicht Secre- 

 tion sondern Sensation zum Zweck." 



Leydig, 1852, also makes three classes of the vessels, one class includ- 

 ing the ducts, another the canals, and another the follicles of Savi. He 

 characterizes them thus : — 



