THE NERVOUS SYSTEM OF THE BIRD 193 
Pr,ATE Figs. 15 — 22 
Fig. 15 Pigeon. Sagittal section, median plane. Weigert stain. 
A. Tr. septo-mesencephalicus. A.ch. Chiasmal fibres of A. A.f. Fornix fibres of A. 
A.C. Anterior commissure. Olf. Olfactory lobe. Op.ch. Optic chiasma. Gd. Gudden's 
commissure. C.p.c. Commissura post chiasmatica. Inf. Infundibulum. Dcc.sup.inf. 
Decussatio supra-infundibularis. P.C. Posterior commissure. ///. Third nerve. 
Fig. 16. Pigeon. Sagittal section, lateral to fig. 15. 
Letters similar to fig. 15. G.Hb. Ganglion habendulae. InfJr. Tractus infundibularis. 
11^. Fourth nerve. 
Fig. 17 Pigeon. Sagittal section, lateral to last. Weigert stain. 
Letters similar to preceding figures. Epith.fb. Epithalamic fibres. Lm.cm.ms. Lamina 
commissuralis mesencephali. E. Tr. occipito-mesencephalicus. 
Fig. 18 Pigeon. Sagittal section, lateral to last. Weigert stain. 
Letters similar to preceding figures. C. Tr. strio-mesencephalicus. C.Ect. Ganglion 
ectomammillare. 
Fig. 19. Pigeon. Sagittal section, lateral to last. Weigert stain. 
Letters similar to preceding figures. B. iff C. Tr. striothalamicus and Tr. strio- 
mesencephalicus. Op.md. median optic bundle. Op.tr. Optic tract. 
Fig. 20 Pigeon. Sagittal section, lateral to last. 
Letters similar to preceding figures. //. Thalamic nuclei. 
Fig. 21 Pigeon. Sagittal section, lateral to last. Weigert stain. 
Letters similar to preceding figures. 
Fig. 22 Pigeon. Sagittal section, lateral to preceding figure. Weigert. 
Letters as above. 
Plate VIL Figs. 23—28 
Fig. 23 Pigeon. Transverse section through fore part of brain. Shows origin of tracts. Weigert stain. 
A. Tr. septo-mesencephalicus. C. Tr. strio-mesencephalicus. F. Tr. occipito-frontalis. 
c.p. Plexus of origin of striate tract. 
Fig. 24 Pigeon. Transverse section, slightly behind preceding figure. Weigert stain. 
Letters as above. 
Fig. 25 Pigeon. Transverse section, behind preceding. Weigert stain. 
Letters as above. 
Fig. 26 Pigeon. Transverse section through hemisphere and optic thalamus. 
Letters as above. B. Strlothalamic tract. Op.Ch. Optic chiasma. 
Fig. 27 Pigeon. Transverse section, behind level of preceding. Weigert. 
Letters as above. = chiasmal fibres of Tr. septo-mesencephalicus. 
Fig. 28 Pigeon. Transverse section through hemisphere and optic vesicle. Weigert. 
A. Tr. septo-mesencephalicus. Op.md. Median optic bundle. Lm.cm.ms. Lamina 
commissuralis mesencephali. P.C. Posterior commissure. For. Forel's fountain 
decussation, int. Internuncial fibres of mesencephalon. 
Plate VIIL Figs. 29 — 39 
Fig. 29 Hen. Transverse section through hemisphere. Slight lesion of hemisphere near mesial surface. 
Marchi stain. 
A. Tr. septo-mesencephalicus. B. Tr. striothalamicus. 
Fig. 30 Hen. Transverse section through hemispheres. Marchi stain. 
A. Tr. septo-mesencephalicus. 
Fig. 31 Hen. Transverse section through hemisphere. Marchi stain. 
A. Tr. septo-mesencephalicus. 
Fig. 32 Hen. Transverse section through hemispheres. Marchi stain. Removal of one hemisphere. 
A.C. Anterior commissure. B. Tr. striothalamicus. C. Tr. striomesencephalicus. A. Tr. 
septomesencephalicus. Op. tr. Optic tract. 
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