76 EVOLUTION OF THE HUMAN EYE 



with the posterior capsule of the lens, and while there form 

 adhesions to it (Fig. 21, B). On the expansion of the 

 globe the ciliary processes become separated from the sides 

 of the lens— a separation which is still further increased 

 on the formation of the anterior chamber, which displaces 

 the lens backward (Fig. 21, C). The growth of the ciliary 

 body away from the side of the lens causes the adhesions 

 which have formed between them to be lengthened out into 

 the fibers of the suspensory ligament. It also, by exerting 

 traction on the anterior and posterior capsule and sides 

 of the lens, causes that structure to alter its shape, so that 

 it loses its spherical form and becomes flattened antero- 

 posterior!}'; the flattening is more marked on the anterior 

 surface than the posterior l>ecause the traction is greater 

 on the anterior capsule than the posterior, due to there 

 being a wider separation of the non-plicated parts of the 

 ciliary body from the anterior capsule of the lens than of 

 the ciliary processes from the posterior capsule. Flattening 

 of the lens antero-posteriorly, due to traction on its anterior 

 and posterior surfaces, increases the curve of its fibers, and 

 keeps them so curved until the traction on the two surfaces 

 is relaxed, i. e., until the suspensory is rendered slack by tin- 

 contraction of the ciliary muscle. The effect of such slacken- 

 ing must necessarily be most on the anterior surface upon 

 which the traction is greatest, and most of all in the central 

 circular area on the anterior surface around which the 

 most anterior of the fibers of the suspensory ligament are 

 attached. 



The farther the backward growth of the non-plicated 

 part of the ciliary body, with the orbiculo-antero-capsular 

 fibers attached to it, the greater will be the traction on the 

 anterior capsule of the lens and the increase of latent accom- 

 modative power. One of the features in the architecture 



