THE EYE. 409 



rig-lit angles to them^ and in this way a rectangular trellis-work is 

 formed. 



The fibrils (nerves of the fourth order) given off by these nerves 

 form networks around the connective-tissue corpuscles^ but no 

 direct connection between nerve and corpuscle has been traced; 

 they always appear to lie on that surface of the corneal corpuscle 

 which is directed towards the superficial surface of the cornea 

 (Klein). In the endothelium covering- the membrane of Descemet 

 these fibrils can be traced coursing along- the margins of the cells 

 (Fig. 255 d), and sometimes underg-oing dichotomous division 

 (Klein). 



Almost all observers have described these fibrils as possessing 

 varicosities ; Hulke, and more recently Wolf, however, deny their 

 presence. Lavdowsky traces nerve-fibrils to the nuclei of the 

 connective-tissue corpuscles. 



(7) The anterior chamber is the space between the cornea and 

 the iris, and is filled with a watery fluid, the aqueous humour. At 

 the circumference of the chamber are a number of spaces (spaces of 

 Fontana), formed by interruptions in the tissue between the poste- 

 rior surface of ■ the cornea and the iris ; the result is that bands or 

 trabeculae {Jlgamentum 2''ect'inatum iridis) pass from the one structure 

 to the other, and between these are the spaces of Fontana. 



According to Angelucci these trabeculae are of three kinds : 

 trabeculae passing from the cornea to the iris, formed of con- 

 nective-tissue ; trabeculae from the cornea to the ciliary processes, 

 which contain elastic tissue ; trabeculae from the interstitial con- 

 nective-tissue of the ciliary muscle to the cornea, and formed 

 almost entirely of elastic tissue. 



At the junction of the cornea and sclerotic, and just in front of the 

 spaces of Fontana, is a larger and similar space, which may be traced 

 round the whole circumference of the cornea; this, the canal of 

 Schlemm (Sinus circularu iridis), is held to be a venous plexus by 

 some observers (Angelucci, and others), according to others it is a 

 lymphatic space in connection with the anterior chamber (Schwalbe, 

 and others). It is certain that the vessels can be very easily in- 

 jected from the anterior chamber, although a direct communication 

 has not yet been seen. 



c. The choroid coat and the iris {tunica choroidta et iris, tunica 

 vasculosa). 



1. The choroid coat lines the deeper surface of the sclerotic 

 coat, but is also prolonged under the cornea to form the iris. 



