3o6 AVERS. [Vol. VI. 



G. Recapitulation of Some of the Topics, with a 

 Further Consideration of a Few Others. 



Recapitulation B. 



I. Since the beginning of this century the idea that the 

 lateral line of fishes was related in some way to the higher 

 sense organs, nose, ear, and eye, one or all of them, has never 

 been absent from the minds of morphologists ; and although, 

 when first expressed, the lateral line was considered to be 

 merely a series of mucous pockets more or less completely 

 joined into a canal without even a suspicion that they had 

 nervous attachments or contained sense organs, still it was 

 believed and categorically stated that since these structures 

 were in line on the side of the body with the higher sense 

 organs on the head, and since they found their place between 

 the dorsal and ventral groups of trunk muscles, they were in all 

 probability related to the higher sense organs. Some authors 

 thought that they were the parental forms ; others that they 

 were derivatives of ancestral organs which were the parental 

 type ; others, again, homologized the " mucous pockets " and 

 canals of the lateral line with the tracheal canals and stigmata 

 of insects, which were then quite generally believed to be 

 auditory in function, and they claimed that the vertebrate ear 

 was the greatly modified product of a mucous pocket which had 

 somehow or other acquired the sensory structures and their 

 accompanying nerves. 



This idea has grown in strength in successive generations 

 with, each renewed investigation, until now, confining ourselves 

 to the ear, it may be said to be fully established. The investi- 

 gations of Leydig in demonstrating the nerve supply of the 

 contained sense organs in these canals, or rather in their 

 " mucous pockets," opened the way for the score or more of 

 workers who have increased our knowledge, and among whom 

 we find the names of Leydig, Ball, Bodenstein, Schulze, Solger, 

 Emory, Dercum, Fritsch, and Allis, some dealing with the 

 morphological data alone, others with the physiological side as 

 well. The one point of general agreement among all has been 

 the o:reat resemblance of the canal sense oro-ans to the maculae 



