274 PRACTICAL HISTOLOGY. 



with the outer surface uppermost. Each includes, 

 of course, the fourth part of the choroid coat with 

 some of the ciliary processes, and a piece of the iris; 

 and with a low power the course and disposition of 

 the bloodvessels in these parts can be readily followed. 

 Besides these comprehensive preparations, separate 

 ones may be made from the other half of the eye of 

 a portion of the iris (this is rendered more instruc- 

 tive by lightly staining it with logwood), and one 

 or two of the ciliary processes snipped off with sharp 

 scissors, and mounted so as to be seen in profile. 



Preparation 40. The vessels of the retina. 

 If the other injected eye be cut into an anterior and 

 a posterior half, and the posterior part is examined 

 after removal of the vitreous humor, the bloodvessels 

 will be seen spreading out from the centre of the 

 colliculus of the optic nerve. To exhibit their finer 

 distribution in the retina, a piece is mounted fiat in 

 dammar without previous staining, while to show 

 the extent of their distribution in the retinal layers, 

 vertical sections, which need not be very thin, may 

 be made from a piece embedded in wax-mass in the 

 ordinary way, and similarly mounted, without stain- 

 ing, in dammar. 



