THE MAMMALIAN NERVOUS SYSTEM 111 



lateral border of the lateral ventricle, note the positions of the 

 stria terminalis (stria or tsenia semicircularis), plexus chorioi- 

 deus of the lateral ventricle and tail of the caudate nucleus. 

 Follow the last three medially and anteriorly, noting carefully 

 their relationships to each other and to the hippocampus, until 

 the anterior end of the head of the caudate nucleus is reached 

 near the region of the anterior perforated space. The stria ter- 

 minalis can be traced forward into the anterior commissure. 

 Tracing the stria terminalis backward into the temporal lobe 

 it will be seen to enter the anterior tip of the gyrus hippocampi, 

 where it ends in a small deep gray mass, the nucleus amygdalce. 

 See Cunningham ('15), Figs. 539, 563; Herrick ('18), Figs. 76 

 and 121; Morris ('14), Figs. 658, 688, 691, pp. 834, 875, 878 

 respectively; Piersol ('16), see references under Section 130; 

 Quain ('09), Vol. Ill, Pt. 1, Figs. 228, 233, 294, pp. 224, 229, 

 294 respectively. 



133. Draw the dissection at this stage, as seen from above, 

 showing the form of the lateral ventricle and the structures 

 which form its walls (cf. Burkholder ('12), Plates XIII-XVI). 



134. Now pulling carefully so as to tear the tissue slightly, 

 draw away the ventricular wall along the upper border of the 

 caudate nucleus. The internal capsule fibers can now be seen 

 passing downward and backward, lateral to the caudate nu- 

 cleus. By teasing away the remaining association fibers on the 

 lateral side of the hemisphere the lentiform nucleus (a large 

 gray mass) will be exposed to view and the internal capsule 

 fibers will be seen passing downward and posteriorly between 

 the caudate and lentiform nuclei. By teasing away the gray 

 cell masses of the lentiform nucleus some of the fiber bundles 

 can be seen passing into the cerebral peduncle (pedunculus 

 cerebri). Care must be taken not to dissect too deeply and 

 thus injure the underlying thalamus, which lies medially of the 

 posterior part of the internal capsule (cf. Burkholder ('12), 

 Plate XXII). 



135. Retina. If microscopic preparations are available, 

 study the histological structure of the retina. From the refer- 

 ence books master the arrangements of its neurons and the 

 course of nervous impulses within it. See Bailey ('16), pp. 

 561-565; Barker ('01), Chap. XXXVII, pp. 532-543; Cunning- 



