332 



which will meet with no further resistance to the expansion of its 

 short axis. 



6. That the lens itself, as microscopically described by Bowman 

 and Kolliker, is admirably adapted to the varying changes which 

 take place in the capsule. 



7. That the posterior capsule being firmly united to the hyaloid 

 membrane, the alteration in the diameters of the cavity of the cap- 

 sule must take place from the periphery of the lens to its centre, 

 and from behind forwards, but not from before backwards, on account 

 of the close union of the posterior capsule to the hyaloid membrane. 



8. That to allow such alteration to take place without endanger- 

 ing the achromatism of the lens, the alterations in the plane of its 

 long diameter must be synchronous with the alterations in the plane 

 of its short diameter. To allow of this, the margin of the lens is free 

 in the canal of Petit ; were it not the case, chromatic aberration 

 would result. 



9. That the elasticity of the capsule of the lens and the ciliary 

 muscle are antagonistic ; that on the ciliary muscle becoming relaxed, 

 the capsule of the lens is free to exert that elasticity. 



10. That, by the pressure exerted by the anterior hemisphere of 

 the capsule by means of the polygonal cells of Virchow on the ante- 

 rior face of the lens, the organ is able to fulfil all the requirements 

 for adapting it to receive focalized light from long distances. 



1 1 . That the polygonal cells of Virchow are placed on the pos- 

 terior surface of the anterior hemisphere of the capsule with the 

 view before mentioned, and that they are arranged with their long 

 diameters in an antero-posterior direction, that pressure may not 

 injure their transparency, which would be the case if placed laterally. 



12. That these cells are not found in other parts of the capsule. 



13. That the fibres of the lens are serrated for the purpose of 

 uniting either to other, so as to allow them greater freedom of 

 motion without altering their ultimate relations to each other. 



14. That the ciliary muscle is very highly endowed with nervous 

 matter to supply all these varying requirements. 



15. By the above postulates, all the modern discoveries in the 

 microscopical anatomy of the eye receive a distinct expression of 

 their individual functions, and, by so doing, adapt the organ of 

 vision to the acknowledged laws of light. 



