Peculiar Structure in the Eyes of Fishes. 139 



16 



In the preparation taken from the eye of the pike, 

 is now in the museum of the Royal College 

 of Surgeons, I found this body supplied by a 

 considerable filament of nerve, which, traced 

 to the posterior part of the eye, was found to 

 enter the sclerotica, in the immediate neigh- 

 bourhood of the optic nerve. The diagram, 

 [fig. 17), represents this preparation. 



This body, if placed between two plates of 

 glass, and carefully expanded by pressure, 

 exhibits, under a good microscope, a granu- 

 lar mass, interspersed with minute blood- 

 vessels, capable of being coloured by a ver- 

 milion and turpentine injection. It is also 

 threaded by filaments of nerve. I have not 

 yet been able to trace distinct fibres, possibly owing to the 

 softness of the mass, it being crushed under even light pres- 

 sure ; no marks, therefore, of the lineae transversa, as seen in 

 ordinary muscular fibre, can be observed. This latter cir- 

 cumstance is no proof of its not being muscular, since although 

 these parallel lines or furrows, when present, are tests of mus- 

 cular fibre, yet they have not been discovered in those of the 

 involuntary class, as in the heart or intestines. 



The pear-shaped body is sensibly hardened by boiling, spi- 

 rits of wine, and acids ; and from the circumstance of its large 

 nervous supply, I am inclined to believe it muscular, although 



