THE EYE OF FISHES. 



265 



On a closer examination, the lens is found to be composed of 

 several thousands of regular transparent laminae or spherical 

 coats of uniform thick- 

 ness: each of these la- 

 minaB consists of about 

 2,500 fibres, extending 

 from pole to pole of the 

 sphere, and being conse- 

 quently widest at the 

 equator. The mode in 

 which these fibres are 

 fastened together, so as 

 to resist separation and 

 form a continuous spheri- 

 cal surface, is very cu- 

 rious ; the contiguous 



Direction ot Fibres in Crystalline Lens of Cod 



fibres being united by (magnified). 



means of teeth, about 12,000 in each fibre, exactly like those of 

 rackwork the projecting teeth of one fibre entering into the 

 hollows between the teeth of 

 the adjacent one. As the 

 fibres gradually diminish in 

 size towards the centre of the 

 lens and the teeth in the same 

 proportion, so that the number 

 of fibres or teeth in any spheri- 

 cal coat or lamina is the same 

 from whatever part of the lens 

 it is detached, it is not diffi- 

 cult to calculate their number. 

 Thus the lens of a small cod, 

 four-tenths of an inch in dia- 

 meter, contains no less than 

 five millions of fibres and sixty- 

 two thousand five hundred millions of teeth ! ' A transparent 

 lens exhibiting such a mechanism,' says Sir David Brewster, 

 who was the first to investigate its wonders, *' may well excite 

 our astonishment and admiration ! ' 



As the eyes of the fishes are perpetually bathed by the water in 

 which they live, we cannot wonder at the lachrymal apparatus 



Teeth of Fibres in Crystalline Lens of Cod 

 (highly magnified). 



