206 The Eye of tie Cod-fish, 



dense mass of extremely fine molecules, agglutinated together 

 by an albuminous fluid, which becomes gradually less dense to- 

 wards the centre of the corpuscular cavity. The half-cone may, 

 therefore, not inaptly be compared to an ovum in which the 

 chorion, yelk-membrane, and granular yelk respectively occupy 

 the same relative position as the parts just described. Such 

 are the appearances ordinarily found on examining the retina of 

 the cod, a small appendage being occasionally visible at one 

 end of the cone (as shown in Fig. 10), which, however, drops off 

 immediately any floating particles strike against it. In the 

 case of the twin-cone (Fig. 15) here represented, there were 

 two appendages adherent, both of which I saw detached in the 

 manner just indicated. Mr. Nunneley, of Leeds, who describes 

 the appendage in question as " the conical leg " of the cone, 

 has noticed similar changes to " occur within a very short 

 time after death •" but notwithstanding the extent of his 

 recent and valuable researches on the retina, the antecedent 

 phenomena which I am now about to detail do not appear to 

 have come under his observation. My attention was first called 

 to a special examination of these cone structures in the cod at a 

 meeting of the Brighton Microscopical Society, held in the even- 

 ing of the 6th of December last, and as I derived great assistance 

 from the distinguished members of that society who were pre- 

 sent, I think it right to allude to the particular circumstances 

 under which certain observations, preceding those I have just 

 recorded, were made ; and in doing this I shall describe the 

 mode of occurrence of a series of phenomena in connection 

 with the cones, which I have subsequently and independently 

 confirmed. I had taken with me to the meeting a perfectly 

 fresh cod's eye, with the view more particularly of re-examining 

 the choroid gland under Mr. Hennah's powerful " Smith and 

 Beck" microscope, which is fitted with Wenham's binocular 

 arrangement. After examining the choroid band, without, 

 however, obtaining any other results than such as I had pre- 

 viously acquired from my own instrument (by Ross), I placed a 

 portion of the retina under the one-fifth objective, when the 

 following facts were elicited : — Conspicuous beyond any other 

 histological element were numerous oval corpuscular bodies, or 

 perfect twin-cones, all of which were slightly truncated at 

 either extremity, symmetrical in form, and divided longitu- 

 dinally by a straight line passing in the middle line from polo 

 to pole (Fig. 16). All of them in the first demonstration 

 exhibited those characters. Following Mr. Henn all's advice, I 

 had in this demonstration only added to the slide a little of the 

 albuminous fluid, which is naturally present in the eyeball, but 

 when this medium was supplanted by the addition of a drop or 

 two of clear, cold, hard water, the effect at once produced upon 



