KYB. 



30.1 



Fig. 128. 



any intervening membrane, it constitutes an from its folded form bearing some rexeniblamv 

 unexpected anomaly in the animal (economy, to a comb, and ;/-s/i/;/i nizriim from IN 

 The consequences of inflammation greatly resemblance in the eye of the ostrich to a Mm k 

 strengthen the conclusion that the cavity is purse, according to the anatomists of tlip 

 lined by a membrane of the serous character. French Academy, who compiled the colli < lion 

 The slightest injuries or even small ulcers of of memoirs on comparative anatomy. The 

 the cornea are frequently accompanied hy eff'u- organ is obviously a screen projected from 

 sion of purulent matter into the anterior the bottom of the eye forward toward the crys- 

 chuniber, from the extension of the inflam- talline lens, and, consequently, received into 

 mation into that cavity, constituting the hy- a corresponding notch or wedge-shaped hollow 

 popion or onyx of the books; and the yellow in the vitreous humour; it appears to be of 

 masses which appear on the iris in syphilitic the same vascular structure as the choroid, and 

 iritis, whether they are abscesses, or as they is deeply stained with the black pigment, 

 are called, globules of lymph, are effusions which renders itperfectly opaque and imper- 

 beneath a delicate membrane, as vessels may vious to light. The annexed figure, from the 

 be seen with a magnifying glass, ramifying work of 1). W. Sommerring, represents it in 

 over them. In iritis the rapidity with which the eye of the golden eagle, 

 adhesions are formed between the margin of 

 the pupil and the capsule, proves that these 

 two structures are covered by a membrane of 

 this nature. In addition to all these facts the 

 still more conclusive one is to be adduced, 

 namely, that the membrane can without diffi- 

 culty be demonstrated on 



the back of the iris, as 



I have stated in speaking 



of that part of the organ, 



and as it is represented 



in fig. 127, where the 



fold of membrane stained 



with black pigment is seen 



turned down from that 



structure. 



In the preceding pages I have availed my- 

 self of whatever valuable and appropriate facts It is composed of a delicate membrane, highly 

 in comparative anatomy I found calculated to vascular, folded exactly like the plaits of a fan, 

 illustrate or explain the structure of the human and when removed with sharp scissors from 

 eye. There are, however, two organs in other the bottom of the eye, and its free margin cut 

 animals which do not exist even in the most along the edge so as to allow the folds to be 

 imperfect or rudimental state in the human pulled open, it may be spread out into a strip 

 subject the pecten or marsupium nigrum in of continuous riband-shaped membrane, as 

 birds, and the choroid gland or choroid muscle seen in jig. 129, from a paper of Sir E. 

 in fishes. Home's in the Philosophical Transactions for 



Of the pecten. This organ is called pecten 1822. 



Fig. 129. 



Fig 127. 



The first account I find of it is by Petit in 

 the Mem. de 1'Acad. Hoy. 1735. He says it 

 is a trapezium or trapezoid, five lines long at 

 the base, and three lines and a half deep, com- 

 posed of parallel fibres, and that a fine trans- 

 parent filament runs from the anterior superior 

 angle to the capsule of the crystalline lens, 

 not easily seen on account of its transparency, 

 and that sometimes the angle itself is attached 

 to the capsule near its margin. Haller, in his 

 work " Sur la formation du cceur dans le 



poulet," describes it as follows: " It is a 

 black membrane folded at very acute angles, as 

 the paper of a fan, upon which transparent 

 vessels are expanded; it generally resembles 

 the ciliary processes. It originates from the 

 sclerotic in the posterior part of the eye by a 

 serrated line, pierces the choroid, retina, and 

 vitreous humour to attach itself to the side of 

 the capsule of the crystalline, very near the 

 corona ciliaris. The posterior extremity is 

 broad, and the anterior narrows till it becomes 



