90 CRYSTALLINE LENS. 



form the primary structure of the crystalline lens, and no 

 fibres can be detected in the early stage, and since the more 

 fully- developed lens of the foetal pig exhibited many fibres and 

 fewer round cells, and at the same time cells which became 

 elongated into fibres, we cannot but regard the fibres gene- 

 rally as elongated cells. It is true that a cell-membrane 

 cannot be distinguished on the fibres, nor can it be distinctly 

 recognized on the round cells. If, however, the arguments 

 above cited rendered its existence in the round cells certain, 

 they must avail equally in the case of the fibres. Nuclei 

 are also frequently found upon the fibres of the foetal pig 

 Some of the fibres are flat. I have, also, several times ob- 

 served an arrangement of the nuclei in rows ; but I do not 

 know what signification to attach to the fact. A blending of 

 several cells to form a fibre may also possibly occur j but I 

 have no observations decisive of the point. In fishes also 

 in a young pike for instance, the elongation of the cells into 

 fibres may often be very distinctly seen. 



Brewster found that many fibres of the crystalline lens espe- 

 cially m fishes, exhibit the remarkable peculiarity of having 

 their margins serrated. PI. I, fig. 13, represents such a fibre 

 taken from the innermost lamina of the lens of a pike The 

 fibres are flat, and their sharp margins furnished with W 

 teeth, which are so disposed, that two neighbouring fibres lock 

 into each other by them. We have here an instance of perfect 

 analogy to a form of vegetable cells, which is delineated in fig 

 14 : it is an epidermal cell of a species of grass. It is very 

 much elongated, quite flat, and furnished on the sides with 

 teeth precisely similar to those of the fibres of the lens which 

 m like manner, fit in between the denticulations of the con- 

 tiguous cells. The fibre-cells of the crystalline lens which are 

 delineated, have somewhat longer teeth in comparison with the 

 breadth of the cell - they represent, however, some of the most 

 strong y denticulated fibres. On pursuing the examination 

 from the external towards the internal laminas, the same lens 

 will be found to present all possible stages of transition in this 

 serration, from the smooth or only minutely -notched cells, 

 to such as are strongly denticulated like those in the figure. 

 Has striking accordance of so remarkable a form of animal 

 structure with a similar modification of vegetable cells, is a 



