150 



A VERS. 



EXPLANATION OF PLATE VII. 



Fig. I. Several hair cells from the basilar organ of the Mocking-bird, to show 

 the effect of reagents upon the hairs, a, the average result of the action of alcohol 

 and hardening acids upon the hairs when care is exercised to preserve them, b, a 

 nearly normal hair, with tip slightly melted down by the acid, c, more modified hair. 

 d, an apparent collar about the base of the hairs of one cell. X 1400. 



Fig. 2. One of the cartilaginous bars and the attached membrana basilaris from 

 the cochlea of the Mocking-bird, showing the two very distinct fibre layers of the 

 membrane, v.s., spiral blood-vessel, e.p., a few of the epithelial cells of the sense 

 organ covering the membrane, i and 2, the lower and upper layers of the basilar 

 membrane. X 380. 



Fig. 3. Three hairs from the papilla lagense of the Mocking-bird, with their 

 basal attachment, viewed in living condition in normal salt solution, with optical sec- 

 tions at a and b. X S50. 



Fig. 4. The proximal end of the membrana basilaris and its frame, from the adult 

 Mocking-bird. X 45- ^i-^-i hair cells of the basilar papilla. The shaded polygons 

 have the hairs indicated, i, 2, 3, the three layers of the basilar membrane. 2, the 

 intermediate layer not shown in Fig. 2. 



Fig. 5. Four hair cells from the papilla lagense. a and b, after the use of 

 hardening reagents, c and d, in the normal condition. X 1400. From the adult 

 Mocking-bird. 



Fig. 6. A single hair cell isolated from the lagenar organ after the usual harden- 

 ing method. The hairs broken off and separated. X 1400. 



Fig. 7. The whole of the cochlear tube of the Mocking-bird, viewed from its 

 neural face, n.c, cochlear nerve, r.p.b., ramus papillae basilaris. rJ., ramulus 

 lagenae. c. and c.', cartilaginous frame, b.v., blood-vessel, s.c, superior transverse 

 cartilage. The left ear from the inside. 



Fig. 8. A single hair cell, alive in aqueous humor, a, terminal bulb of hair 

 affixed to cover glass, b', the elastic hair, c, the cell cap. 



Fig. 9. The same cochlear tube seen from the outside, on its vascular face. 

 Letters the same as in Fig. 7^ 



Fig. 10. A nearly vertical section of the developing ear of a 32-day Salmo fario 

 embryo. X II4- d.e., ductus endolymphaticus. m.d., the floor of the medulla. 

 m.o., the roof of the mouth, c.r.p., c.r.a., and c.r.e., the three cristae acusticae, 

 posterior, anterior, and external, respectively. <?., eye. The blood-vessels and lymph 

 spaces below the cristas are distinctly seen, as well as the nerve to the anterior am- 

 pullar sense organ, which appears in section. 



Fig. II. The crista acustica of the ampulla of the Mocking-bird, seen from the 

 side, a.c, p.c, and I.e., the apical, axial, and lateral crests of the structure, the latter 

 passing out into the planum semilunatum. X 45- The sensory hairs cover the 

 whole surface of the structure, but appear in this figure only around the edges. 



Fig. 12. Three cells from the papilla basilaris of the Mocking-bird, to show the 

 relation of the sensory hair to the surface of the cell during the action of reagents. 

 X 2800. In cell a two hairs have not yet been affected, while all. others have been 

 melted down at their tips, leaving a bead of varying shape as the representative of 

 the slender hair. 



Fig. 13. Otolithic crystals from the papilla lagense of the Mocking-bird, a, b, c, 

 d, the several shapes and sizes of the crystals observed. X 850. 



