able that by
breaking the stream of air passing through the chink of the glottis,
they also exercise considerable influence upon the _quality_ of the tone
emitted. It may be affirmed, however, without the slightest hesitation,
that they have absolutely nothing to do with the _production_ of tone.
We shall see these glandular ledges again during our observations upon
the living subject, and I shall therefore say no more about them at
present.

[Illustration: PLATE XII.

VIEW OF THE VOICEBOX, OR LARYNX, WHICH HAS BEEN CUT OPEN FROM BEHIND.

1, 2. POCKET LIGAMENTS (FALSE VOCAL CORDS).

3, 4. VOCAL LIGAMENTS (VOCAL CORDS).

5, 6. SHIELD (THYROID) CARTILAGE.

7, 8. CARTILAGES OF SANTORINI.

9. LID (EPIGLOTTIS).

14, 10 & 15, 11. FOLDS OF MUCOUS MEMBRANE (ARYTENO-EPIGLOTTIC FOLDS).

12, 13. WEDGES (CUNEIFORM CARTILAGES).

14, 15. CARTILAGES OF WRISBERG.

16, 17. PYRAMID MUSCLE (ARYTENOIDEUS TRANSVERSUS).

18, 19. RING (CRICOID) CARTILAGE.

20, 21. TONGUE (HYOID) BONE.
]

The space between the pocket ligaments and the vocal ligaments (pl. XII,
1, 2, 3, 4) is the entrance to two pouches or pockets which extend
outwards and upwards. The dimensions of these pockets vary very much in
different individuals. As a rule their height does not exceed two-fifths
of an inch, so that their terminations do not reach the upper borders of
the shield cartilage (pl. XII, 5 and 6). But there are instances in
which the pockets are nearly three-quarters of an inch high, and where
such is the case they, as a necessary consequence, reach beyond the
shield. Sometimes they are so high as nearly to touch the root of the
tongue. Their outer walls are chiefly formed of loose fatty cellular
tissue, and the pockets are almost entirely surrounded by a large number
of small glands.

Now these are the "Laryngeal sacculi" which, according to Mr.
Illingworth, produce the falsetto voice by "acting in the same way
as a hazel-nut can be made to act as a whistle, when the kernel has
been extracted through a small hole in the shell," &c. I think,
however, that the reader will, from the description given above,
agree with me that the acoustic properties of the pockets of the
voicebox cannot be very great, and that, at all events, there is a
vast difference between their construction and that of a hazel-nut,
either with or without the kernel. Then there is this additional
difficulty, that even if o