9 



tributes to the formation of these fibers, especially the cells oppo- 

 site the region where retina and pigment layer meet. On the ante- 

 rior surface of the lens, some of these fibers penetrate deeply into 

 the surrounding mesoderm with which they frequently unite ; others 

 even find their way to the overlying body ectoderm. In the more 

 advanced stages of development, when the lens capsule begins to be 

 formed as a secretion of the lens cells, the lenticular fibers gradually 

 lose their connection with the basal cells of the lens. The light 

 space between the lens and the feltlike mass of fibers described above 

 (Figure 1) signalizes the region of the future tunica vasculosa 

 lent-is, or vascular capsule of the lens. 



The vitreous body at this stage of development, therefore, con- 

 sists of fibers, both radial and parallel, which, springing from the 

 conelike projections of the basal cells of the retina and lens, form 

 with frequent anastomoses a dense network, or rather framework, 

 constituting the solid or structural part of the vitreous body. These 

 fibers arise solely as protoplasmic prolongations of the retinal and 

 lenticular cells and are, therefore, ectodermal in their origin. No 

 mesodermal elements contribute to their production. 



We can not agree, therefore, with Scholer and his followers in 

 their contention, that the vitreous body takes its origin from the 

 mesoderm entering through the choroid fissure ; for in all embryos, 

 examined at the various stages of development up to 12 mm length, 

 no mesoderm was found to have entered into the optic cup through 

 the choroid fissure. The cells found here and there in the vitreous 

 body, whatever their origin, nature, and ultimate fate may be, take 

 no part in the production of the primitive vitreous body fibers, nor 

 do they, at this stage, enter into any connection with them. The 

 fibers can be traced so easily to the basal cells of the retina and 

 lens that their retinal and lenticular origin respectively, at this 

 stage of the development of the eye, admits of no doubt. 



Cirincione maintains that these fibers are only temporary, and 

 that their sole purpose is to fill out the cavity of the optic cup until 

 the permanent vitreous body is formed by the mesoderm entering 

 later through the choroid fissure. He admits the presence of the 

 retinal and the lenticular fibers, and concedes their origin from the 

 basal cells of the retina and lens, but regards them only as a 

 sostanza di replezione destined to disappear in the same degree as 

 the mesodermal elements advance into the cavity of the secondary 

 optic vesicle to form the vitreous body (page 1,358). But further 



