508 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCTETY. 
perforated by small holes, and consist of a thin layer of 
connective tissue covered on either side by the secretory 
columnar epithelium. An oblique diaphragm limits the 
region of the gland, and is perforated by a hole for the 
passage of the ink. At the base of the gland is found a 
whitish mass of round non-glandular cells (fig. 26, gld,). 
This is the formative region where the trabeculae 
originate. The initially indifferent cells become differen- 
tiated into either the connective tissue or the secretory 
cells of the trabeculae. These trabeculae are constantly 
being formed and travelling forwards to the anterior end 
of the glandular region. Tracing their course and 
structure as they go, it is found that the young cells 
eradually accumulate pigment granules, and when they 
are full burst. Thus the ink is freed and the secretory 
cells destroyed. ‘Towards the anterior end of the gland, 
then, the trabeculae disintegrate, and are constantly 
replaced by the younger ones behind (Girod). The 
secretion 1s a thick dark-brown liquid, and a few drops 
will colour a large volume of water. On drying, a dark- 
brown powder is obtained. ‘The liquid consists of a 
colourless transparent plasma, having minute dark- 
brown pigment granules in suspension. On analysis it 
is found to contain both copper and iron, extracted from 
the blood (Girod). Although the actual secretion of the 
ink is continuous, its passage to the exterior is 
intermittent and voluntary. After expulsion from the 
anus, the ink is discharged, along with a jet of water, 
through the funnel. 
