TISSUES OF THE BODY. 



277 



Fig. 266. Fibres of the hu- 

 man lens, a, from the cir- 

 cumference; and b, from 

 the more central part. 



cylindrical, but more or less flattened (fig. 266, a). This is, however, 

 most evident when we take the transverse section of a dried lens (fig. 267) 

 for our object. Here we find the several tubes most delicately marked 

 out as compressed hexagonal figures, measuring 

 0-0113-0-0056 mm. in breadth. 



Looking now to the arrangement of the fibres 

 (fig. 265), we find them placed meridionally, pass- 

 ing from the middle portion of the anterior half 

 of the capsule over the equator of the organ to a 

 corresponding point on the posterior half. Their 

 broad surfaces are always directed outwards, and 

 their borders are closely applied to those of ad- 

 jacent fibres. Owing to the latter union being the 

 stronger of the two, whole layers of fibres can be 

 peeled off from the lens in the form of delicate 

 concentric lamellae, which follow at the surface of 

 the organ the greater curves of the latter, while 

 within they are more circular. 



In perpendicular sections of hardened lenses the fibres (fig. 265, c) are 

 seen to spring up with a broad extremity (d) under the epithelial coat- 

 ing (b) of the anterior wall, and then, pursuing their curved course, to 

 end in a similar manner by insertion into the posterior half of the capsule 

 (e), which is devoid of cells (2). In following up this course of the fibres, we 

 remark in the neighbourhood of the equator of the organ, in each, a beau- 

 tiful rounded vesicular nucleus (/), about 0-0074-0-0129 mm. in diameter. 



A glance through the transparent tissue down upon this arrangement 

 of the nuclei, the " nucleus zone," of H. Meyer, is one 

 which well repays the observer for the trouble of 

 preparation. The statement, however, that each fibre 

 of the lens possesses only one nucleus is not correct 

 in all cases (see below) : in a foetus of eight months 

 old I myself have seen them with two or three, most 

 distinctly visible (fig. 270). 



We must not, however, picture this nucleus zone to ourselves as a 

 diaphragm occupying the equatorial plane ; it resembles far more a leaf 

 attached at the periphery, which is continued inwards in an undulating 

 course, at regular distances from the rays of the "lens star," to be referred 

 to immediately (von Becker.} 



The cloudy organ of the infant (fig. 268) presents for our consideration 

 a very peculiar arrangement in its structure 

 in the relations of the so-called ' lens 

 stars." In the centre of the anterior sur- 

 face (a), namely, we perceive three bands 

 meeting together at an angle of 120, 

 forming a three-rayed star or inverted Y. 

 On the posterior wall, either a similar 

 figure reversed is met with or that of a 

 four-rayed star (b). In the first case the 

 arms of the posterior Y occupy a position in relation to the anterior 

 as though turned on their axis to the amount of 60. Later on in life 

 each of these rays subdivides at acute angles into regular series of 

 branches, giving rise to complicated stellate figures. 



The microscope teaches us that within such a ray and its system of 



Fig. 267. Transverse sec- 

 tion of the fibres of a 

 dried lens. 



oo 



Fig. 268. Lens from an infant, a, the 

 anterior ; 6, the posterior surface. 



