460 



occurrence of an adult specimen in which such a mass was actually 

 being extruded in the form of "mucus" into the cavity of the eye to 

 take part in the formation of the vitreous body. I have observed 

 this extrusion of "mucus" into the cavity of the eye in several cases, 

 and as early as stage R. With the "mucus", nuclei may pass out 

 from the lens, and there can be no doubt that the secretion is formed 

 by degeneration of cells in the middle of the lens. The extrusion 

 always appears to take place from the middle of the lower surface 

 of the lens at a very definite spot, but an actual aperture is probably 

 present only at the time when the secretion is being poured out. 



The vitreous body always contains, in preparations, a reticulum 

 of slender fibres or thin lamellae, and some of these are attached, on 

 the one hand, to the inner surface of the lens, and, on the other, to 

 the inner surface of the retina, apparently in may cases to the pro- 

 jecting ends of sense-cells, but probably really to the caps which cover 

 these. Whether the presence of this reticulum is due to post-mortem 

 changes or not remains an open question. 



A large amount of time has been devoted to following out the 

 course of the nerve of the pineal eye, and I have been able to 

 demonstrate very clearly that it is not a median structure, but belongs 

 to the left side of the body— another striking piece of evidence in 

 favour of the paired origin of the pineal organs. 



In the adult animal the anterior end of the nerve, like the eye itself, 

 has been shifted into the middle line. For the greater part of its 

 course, however, it lies between the wall of the pineal sac and the 

 wall of the dorsal sac, and considerably to the left side of the middle 

 line. It is very easy to follow it from the eye towards the brain up 

 to a certain point, where it breaks up into a number of separate 

 strands. This point lies between the posterior wall of the dorsal sac 

 and the anterior wall of the pineal sac, not far from the lower extre- 

 mity of the latter. Up to this point it consists of a well-defined 

 bundle of non-medullated nerve-fibres, with a definite sheath of con- 

 nective tissue in its more anterior portion, and with numerous elon- 

 gated nuclei lying between the nerve-fibres. It exactly resembles an 

 ordinary non-medullated nerve, and I can see no reason for regard- 

 ing it as exhibiting degeneration. The separate strands into which 

 it breaks up at the point mentioned, however, do not contain the 

 characteristic elongated nuclei, which doubtless really belong to asso- 

 ciated connective-tissue or nutrient cells, and owing to the slenderness 

 of these strands, and the difficulty of distinguishing them from the 



