468 AUGUSTA LAMONT ON 



Acknowledgments are due for assistance granted from the Earl of Moray's 

 Endowment for the Promotion of Original Research, University of Edinburgh. 



2. Historical. 



The first observer to record the occurrence of the so-called " mucous canals " was 

 Nils Stenson, who in 1664 and 1669 makes mention of having seen their openings 

 in Raia, Canis carckarias, and Galeus Isevis ; but it was the Italian, Lorenzini, who 

 first gave a definite description of the " ampulla?," — as he named them — and their 

 canals, and who assigned to these structures, in his work on Torpedo in 1678, a 

 secretory function. The term " Lorenzinian ampullae," therefore, first made use of 

 by Boll nearly two hundred years later, with justice associates these organs with 

 their discoverer. 



No further work on the subject appeared until Monro, after more than a century, 

 published in 1785 his Structure and Physiology of Fishes. In it he described and 

 figured for the skate a pair of groups of radiating ducts containing a viscid 

 mucus and possessing a rich supply of nerves, and these structures he classed as 

 glandular organs. 



The next investigator was Geoffroy St Hilaire (1801), whose work led him 

 to the conclusion that the gland-like masses and radiating canals of Raia rubus were 

 the homologue of the electric organs of the Torpedo. 



The work of Jacobson (1813) presents a considerable advance on that of his pre- 

 decessors. He was the first to record the occurrence of five pairs of " central 

 organs " (groups of ampullae), to mention the presence of similar organs throughout 

 the sharks and rays, and, repudiating former theories, to class them as organs of 

 touch adapted for the perception of undulatory motion. He compared these organs 

 to the vibrissas of birds and mammals, and stated in support of this comparison that 

 both series of structures are supplied by the same branch of the fifth nerve. 



G. R. Treviranus, who followed (1819), agreed with Jacobson in classing the 

 ampullary structures as sense organs, but, demurring at attributing to them a tactile 

 function, hinted at the possibility of a sense other than the five possessed by man. 

 His observations were made on Squalus acanthias, Raia batis, and R. rubus, and he 

 was the first to observe the partitioned structure of the ampullae. 



Another supporter of Jacobson's theory was found in Blainville (1822), who, 

 in his work on Comparative Anatomy, treats of the " tubular organs " (ampullary 

 canals) of Selachii generally under the heading of " active organs of touch." He 

 clearly distinguished between these "tubular organs" and the "lacunar system" 

 (lateral canal system), but appears to have recognised only three pairs of ampullary 

 capsules, and fell into the curious mistake of supposing that these capsules — apart 

 from the canals — were the possible homologue of the electric organ of Torpedo. 



Shortly after Blainville, Robert Knox (1825) wrote on the theory of a sixth 



