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the naked eye, and thirdly because the spine, being curved 

 somewhat, cannot be laid so flat for manipulatiou as the 

 straight opercular ones. In order to examine the fin glands, 

 lay a spine upon its posterior part, and, having fixed it as 

 well as possible, draw the point of the knife along its an- 

 terior prominence from base to point, reflect the integument, 

 and the gland may then be scraped from its groove with the 

 point of a needle. 



Sometimes, in manipulating the gland, all, or in part, comes 

 out of the groove, and it must then be searched for by scraping 

 that part of the inner surface of the integument which forms 

 the sheath, along that part of it which Lies just over the grooves. 

 It rarely happens that the structure can be removed in its 

 integral state; this is more especially the case in the very 

 recent fish, because the structure is quite transparent, and it 

 is rather by knowing where it lodges than by actual inspec- 

 tion, that our attempts to secure it upon the needle are to be 

 directed. In cases where the tissues have been in spirit, the 

 gland has a more lobulated appearance, which appears to be 

 brought about by the spirit coagulating the albumen of the 

 structures, and so corrugating them that the tubes are bent 

 upon themselves, and formed into knuckles as it were. The 

 tubes of which the glands are composed, are about the size of 

 the urinary tubes of the kidney, but their walls are much 

 thinner. In the interior of these tubes, I have once or twice 

 observed the lining membrane to be studded over with 

 small cells having a light pink tinge, they were of different 

 sizes; some were round, others pointedly elliptical; they were 

 observed only in the freshest fishes, and may probably be oil 

 globules. 



As neither general excretory duct nor external openings to 

 the tubes of the gland have been demonstrated, it is still a 

 matter for speculation how the poison becomes diffused into 

 the channels of the spines when these weapons are used. The 

 groove of the spines, together with the integument which 



