THE EYE. 755 



in the fresh vitreous body no trace of them is perceptible, the appear- 

 ances produced by this second reagent can likewise not to be considered 

 as proving much. 



A more correct notion of the constitution of the vitreous body would 

 appear to be derivable from the study of its development. It has been 

 long known that the vitreous body in the foetus has vessels on its sur- 

 face and in the interior ; it might thence have been concluded that some 

 tissue for the support of these vessels must also exist but no one has, 

 till recently, sought farther information with the aid of the microscope. 

 Bowman was the first (1. c., p. 100 and p. 97, Fig. 7) to remark, that 

 the vitreous body of the new-born child exhibited a very distinct and 

 peculiar fibrous structure, consisting in fact of a close network of fibres, 

 presenting at nodular enlargements [where the fibres join] "minute 

 nuclear granules resembling oil-particles, but not soluble in ether;" 

 the whole exhibiting " a peculiar fibrous texture not at all unlike that 

 of the enamel pulp" in the foetal tooth-sac, that is to say, to its gelati- 

 niform connective tissue. This agrees pretty nearly with what Virchow 

 has recently found. According to the latter author, the vitreous body 

 of a foetal Pig, 4 lines long, consists of a homogeneous substance, con- 

 taining mucus, and faintly striated at distant spots, in which round 

 nucleated granular cells lie, scattered at regular distances apart. This 

 substance is surrounded by a delicate membrane, with very elegant vas- 

 cular networks and a fine fibrous areolated mesh-work containing nuclei 

 at the nodular intersections, and also enclosing in its meshes a gela- 

 tinous mucus with rounded cells. Consequently, and also because he 

 found mucus in the vitreous body in the adult, Virchow believes that 

 the tissue of the foetal corpus vitreum should be ranked with what he 

 terms "mucous tissue," corresponding with my gelatinous connective 

 tissue ( 24) ; and that it might be assumed that, in the course of de- 

 velopment, the structure may so change that the cells disappear and the 

 intercellular substance alone remains. As regards my own views, I can 

 only partially agree with these authors. In the vitreous body of the 

 human foetus and of that of animals, I can perceive nothing but a homo- 

 geneous matrix containing mucus and numerous round or elongated 

 granular, nucleated cells, O-004-O'Ol of a line in size, dispersed in it at 

 pretty regular distances of 0-01-0-02, or even 0-03 of a line apart. It 

 is true I have also noticed stelliform anastomosing cells also, but only 

 on the outer side of the hyaloid membrane, and which when the vessels 

 once began to convey blood, could be easily shown to communicate with 

 them, and to be, in fact, capillaries in process of development. Of 

 membranes, such as Hannover describes, I have never seen any certain 

 indication with the microscope ; and yet such membranes, did they 

 exist, would incontestably be as easily recognized, where they are 

 folded, as the excessively delicate hyaloid membrane itself. In the 



