CRYSTALLINE LENS. 



443 



coagulable albuminous matter, 35.9 alcoholic extract with 

 salts, 2.4 watery extract with traces of salts, 1.3 membrane 

 forming the cells, 2.4 water, 58.0. The liquid contained in 

 its cells is more concentrated than any other in the body. y The 

 albuminous matter is peculiar, inasmuch as the concentrated 

 solution instead of becoming a coherent mass on the applica- 

 tion of heat, becomes granulated, exactly as the coloring 

 matter of the blood when coagulated^ from which it only varies 

 Fig. 198. in the absence of color; 



it differs also from fibrine 

 in not coagulating spon- 

 taneously. 



The lens, which at first 

 sight appears to be a sim- 

 ple homogeneous body, 

 more consolidated so as 

 to form a sort of nucleus 

 at the centre, is in fact 

 organized like other parts 

 of the body. The con- 

 centric lamellae of which 

 it is composed are re- 

 solvable into fibres. The arrangement of these fibres differs 

 in the different classes of animals ; according to Sir D. Brewster, 

 in birds and some fishes, as the cod and haddock, the fibres 

 converge in straight lines, from the two opposite poles of the 

 spheroidal lens, like the meridians of a globe. In some other 

 fishes, in reptiles, and a few of the mammalia, the fibres do not 

 start from a single point, but from two septa? at each pole. 

 The third or more complex structure exists in the mammalia 

 in general, in which three septa, as in fig. 198, diverge from 

 each pole of the lens, at angles of 120 degrees ; the septa of 

 the anterior surface bisecting those of the posterior. The 

 mode in which these fibres are laterally united, is very inti- 

 mate by a sort of reciprocal indentation or rack-work. The 

 lens in its embryonic development, is formed in three sepa- 

 rate parts, which are subsequently united at the poles. If the 



