STUDIES IN THE RETINA. 75 



of amorphous matter. In b, exactly similar bodies arise entirely 

 from the inner edges of the i.r. The trumpet shape is due to accidental 

 compression of the section. 



Fig. 27. — From a very old dog, showing the same as Fig. 26, b, i. e. the 

 inner expanded ends of the so-called " Miiller's fibres" arising entirely from 

 the i.r. Matter obviously belongiug to the vitreous humour is seen flaking off 

 the membraiia limitaus interna. 



Fig. 28. — From a rat, 3 years old (Flemming). a. To siiow Ihe flnking off of 

 matter from the membrana limitaus interna ; the flakes show a delicate texture ; 

 the ends of the " Miiller's fibres " filled with amorphous matter, and rising from 

 various depths in the i.r. h. To show the thickening of all strands and mem- 

 branes indifferently, with matter coming from the i.r. c shows " Miiller's 

 fibres" botli losing themselves and starting again within the i.r. 



Fig. 29. — From a rabbit (Hermann), a. From a tangential section, to show 

 a portion of the membrana limitans interna divided into differently darkened 

 areas representing the covers of the conical expansions of the " Miiller's fibres." 

 b. Two conical expansions with cross-sections showing the " fibres " as solid, and 

 witli the tangential strands of the i.r. running into them. 



Fig. 30. — From a mouse which had been exposed to an electric arc lamp. 

 A thick strand of amorphous matter winds its way through the cytoplasmic 

 reticulum jusi inside the o.r., eventually giving off, and bending up into 

 typical " Miiller's fibres." 



Fig. 31. — From a chacma baboon, a. From an old male, with dense 

 black pigment, which not only half fills the large inner limbs of the rods, but 

 streams inward as far as o.r. without changing colour, b. From a young 

 specimen, 3 months old, with yellowish. brown pigment, which also streams as 

 far as the o.r. without changing its colour. 



Fig. 32. — F'rom the human retina, a. From a purchased preparation ; apj)a- 

 rently of an old retina, showing an enormous development of the " Miiller's 

 fibres," a very coarse inner reticular layer, and very few nuclei in the m.n. 

 b. From a "normal healthy " retina of a man 4S years old, which had appa- 

 rently been little used for some time prior to excision. Typical " Miiller's 

 fibres" wholly wanting. Faint streams, often zigzag, and parts of 

 streams alone occur, many of them processes irom the so-called " ganglionic 

 cells." The m.n. was five nuclei deep ; compare the number in u. 13ut for 

 this latter comparison to be of weight we ought to know how far from the 

 centre of the retiua the parts shown were severally taken. 



