183 Dr. Karry's renewed Inquiries concerning the 



a sort of tunnel, through which water is driven by their vehe- 

 ment movements. So much for conclusion No. 3*. 



On the siibject of functions it is also to be remarked, that the 

 pellucid sjjace, fig. 36 h, over which these two lines of cilia, n 

 and 0, move so vehemently, belongs to the membrane of the bar 

 (known to be considered as a vessel of the gill), which membrane 

 is probably destined to absorb oxygen from the water and com- 

 municate it to the blood. This would be materially assisted 

 were the stream of water accelerated, and a fresh supply of 

 oxygen constantly aflforded. 



It must further be remembered, that, as is known, the direc- 

 tion of the current in neighbouring bars is different. If in one 

 it is from the base of the gill towards its margin, in the next it 

 is from the margin towards the base; in the one case appearing 

 to end at a round projection covered with vibrating cilia, 

 fig. 41 qq, — in the other appearing to begin there. The direction 

 of the currents now mentioned as opposite in neighbouring bars, 

 is also opposite on the two sides of the same bar, figs. 37, 38 1- 

 The roiind projection, fig. 41 qq, just refeiTcd to, Sharpey has 

 not particularly mentioned. It seems to be of the same nature 

 as his " round projections," q in the same fignre, with this dif- 

 ference, that where the two bars pass into one another at their 

 ends, two round projections pass into one. Hence the larger 

 size of that at qq, fig. 41 . 



The marvellously complicated movements of the cilia n and o, 

 figs. 36, 37, 38, 41, the author says he has very often observed, 

 continuing to watch them until they became slower, and at length 

 ceased. At last only groups of them are seen thus moving, then 

 not more than two or three together, and finally single ones. 



* The cilia o, as an independent line, Sharpey appears not to have ob- 

 served ; he mentions and figui-es merely the ciUa n, as is evident from the 

 following : — " The motion of the other set consists in a succession of un- 

 dulations, which proceed in a uniform manner along the sides of the bar 

 from one end to the other. It might be very easily mistaken for the cir- 

 culation of globules of a fluid within a canal, more especially as the course 

 of the undulations is different on the twc sides of the bar, being directed 

 on one side towards the edge of the gill, and on the other towards the base. 

 But besides that the undulations continue for some time in small pieces cut 

 off from the gill, which is inconsistent with the progression of fluid in a 

 canal, the cilia are easily distinguished when the undulatory motion becomes 

 languid. When it has entirely ceased, they remain in contact with each 

 other, so as to present the appearance of a membrane [d, d, fig. F) ." — 

 Sharpey, /. c. p. 623. 



So fai- Dr. Sharpey. And the author adds, that he is not aware of any 

 other observer having made any mention of them, — the cilia o. 



t [This fact also is already known.] 



