302 



THE EYE IN EVOLUTION 



is suspended pendulum-like by a firm suspensory ligament, a con- 

 densation of the anterior vitreous with a fibrillar appearance on 

 microscoj)ic examination (Harms, 1928 ; Teulieres and Beauvieux, 

 1931 ; Koch, 1952). Ventrally, at the ciliary end of the falciform 

 process, a small structure of great variability in size and shape makes 

 contact with the lens by ligamentous condensations of the vitreous — 

 the CAMPANULA of Hallcr (1762). It contains a triangular muscle of 

 smooth fibres of ectodermal origin being derived from the retinal 

 epithelium of the ciliary zone at the open lips of the fcetal fissure, thus 

 resembling in this respect the muscles of the iris (Nussbaum, 1901 ; 

 V. Szily, 1922), and is innervated by a short ciliary nerve from the 



Fig. 336. — The Anterior Segment of the Eye of the Bull-head, 



CoTTVS BCBALIS. 



i, iris ; si, suspensory ligament ; s, serous spaces behind the annular liga- 

 ment ; ca, scleral cartilage ; co, conjunctiva ; c, cornea ; p, posterior layer 

 of the cornea ; CH, campanula of Haller (after a drawing by Rochon- 

 Duvigneaud). 



Scorpcena 



ciliary ganglion (TretjakofF, 1926 ; Meader, 1936). It has been 

 generally accepted as being the effector muscle in the accommodative 

 mechanism, acting by retracting the lens towards the retina, a claim, 

 however, contested by Bourguignon and Verrier (1930) who failed to 

 find muscular tissue in this somewhat peculiar structure. Whatever 

 its true nature, it is a characteristic of Teleosteans, being absent only 

 in a few species such as the eel. 



An additional muscle is found in this region in practically all 

 species — the tensor CHOROiDEiE. It was initially described as being 

 composed of fibrous tissue and named the " ciliary ligament " (Leydig, 

 1853 ; Leuckart, 1876), but has been shown to contain smooth 

 muscle fibres (Grynfeltt, 1910 ; Rochon-Duvigneaud, 1943). It is 

 a tenuous muscle, about 1-5 mm. in length, lying between the sclera 

 and the uvea, arising from the annular ligament anteriorly, thus 

 clioring itself to the cornea, and inserting itself into the anterior 

 i^ ri of the choroid just behmd the ora (Faravelh, 1890-91 ; Grynfeltt, 

 It;'') ; in the scorpion-fish, ScoriKena, there is an additional shp 



