472 AUGUSTA LAMONT ON 



system has become predominantly secretory. He, however, considers it possible that 

 the ampullae may at the same time be organs of sense, although he holds that the 

 variability of their structure in the different types of Selachii is to be taken as 

 evidence against this view, seeing that sensory epithelia are of noticeably similar 

 structure even in classes of animals whose relationships are only remote. 



As a result of the work of Ewart (1889-1891) on the cranial nerves and lateral 

 sense-organs of Elasmobranchs, the innervation of both the sensory canals and the 

 ampullae by nerves of the facial complex, and not by branches of the trigeminus, 

 became established. His figures of the sensory canals of Laemargus and Rata batis, 

 and their supplying nerves, also show the relative position and the associated innerva- 

 tion of the ampullae, and his naming the groups of ampullae after their supplying 

 nerve-branches instituted a system of nomenclature by means of which the ampullary 

 groups can be homologised in different types of Selachians. 



Fuchs (1895) was the first since Davy in 1839 to institute experiments with 

 the object of elucidating the vexed problem of the physiology of the ampullae. His 

 experiments, which were carried out on live specimens of Torpedo and Raia, took 

 the form of severing the supplying nerve-branch on one or both sides, applying 

 pressure, heat, and acids, and stimulating the organs after they had been laid bare. 

 The results were negative in all cases except that of pressure applied to the nerve 

 supplying Savi's vesicles, and Fuchs therefore concluded that as a result of his 

 experiments the ampullary system must be denied the sensory function. Later, the 

 experiments were judged by Brandes to have proved nothing at all. 



In 1895 Collinge, in a paper on the sensory and ampullary canals of Chim&ra, 

 maintained that the innervation of the ampullae is from the trigeminus only, and 

 was severely criticised by Cole for perpetuating this old error. In the following 

 year Cole published the results of his own work on the cranial nerves of Chimajra, 

 in which the innervation of the ampullae from branches of the facialis is clearly 

 described. 



During the following ten or twelve years several works appeared dealing with 

 the histology and development of the ampullae. Peabody in 1897 published a well- 

 illustrated abstract of results obtained from work on Galeus canis. giving the most 

 complete account that had till then appeared of the histology of the ampullae, and 

 describing more fully and clearly than had hitherto been done the manner of the 

 nerve-endings. 



Brandes, in 1898, also published a preliminary note on his work on the ampullae 

 of Elasmobranchs generally, confirming all Merkel's histological results, including 

 the presence of a ciliated epithelium (denied by Peabody), but interpreting the 

 " pear-shaped " cells as being glandular and the " cover" cells as sensory. 



Forssell, in a publication which appeared in 1898, gives a very complete account 

 of the anatomy and histology of the ampullae of Acanthias vulgaris. His conclusion 

 is that a sensory function is to be attributed to the epithelium of the ampullae, but 



