53S THE RABBTT chap. 



and its extensions into the frontal, parietal, and temporal lobes. 

 Note :— 



1. Tlie hippocampus, the corpus strialu/n, the choroid plexus, and 

 the septum lucidum (p. 514).' Then cut away the rest of the same 

 hemisphere so as to expose — 



2. a. The dienceplialou and its two lateral halves (optic thalami) 

 between which the third ventricle is enclosed ; from its roof the stalk 

 of the pineal body arises ; b, the two pairs of optic lobes. Cut away the 

 lateral half of the cerebellum of the same side, and note — 



3. The valve ai Vieussens, the fourth ventricle, and the tree-like 

 appearance (arbor vita) of the cerebellum in section. 



III. Now reduce the whole brain to a longitudinal vertical section 

 (Fig. 132), cutting it through with a sharp knife very slightly to that 

 side of the median line which you have already dissected, so as to 

 expose the median ventricles in section. Make out, on the uninjured 

 half, the relations of the third ventricle, iter, fom-th ventricle, foramen 

 of Monro, inftmdibulum, optic chiasma, corpus callosum and fornix, 

 lamina terminalis, anterior, middle, and posterior commissure, crura 

 cerebri, valve of Vieussens, pons Varolii, i^c. Sketch. 



IV. A series of thick transverse sections should be made through 

 another thoroughly hardened brain, and the relations of the parts 

 already seen by dissection examined. 



H. The Eye. 



On account of its larger size, it is better to suljstitute the eye of an ox 

 or sheep — which can be obtained fresh from a butcher — for that of the 

 rabbit. Two specimens should be obtained, and the fat, muscles, 

 and any portions of the eyelids remaining attached cleared away. 

 I . After noting the conjunctiva, cornea, sclerotic, optic nerve, iris, and 

 pupil, insert the scissors into the margin of the cornea and cut round 

 and remove it, so as to expose the aqueous chamber, noting the aqueous 

 humour, as well as the iris, lens, and pupil (compare Fig. 57)- 

 Sketch. 



Insert the handle of a scalpel between the iris and sclerotic and 

 separate off the latter from the choroid around the outer half of the eye- 

 ball, first making four radial cuts in the sclerotic, beginning at its 

 margin, at equal distances from one another. Turn back the four flaps 

 thus made, and insert pins through them so as to fix [the eye firmly 

 down under water with the iris uppermost : note the ciliarv 7mtscle around 



