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YI . — On the Lachrymal Gland of the Common Turtle. 
By C. Stewart, F.L.S., Hon. Sec. R.M.S. 
( 'Talcen as read before the Royal Microscopical Society, Nov. 7 , 1877 .) 
Plate CO. 
In dissecting the head of the common turtle ( Chelone midas ) one 
cannot but be struck by the great relative and absolute size of 
the lachrymal gland. The large size of this organ is the more 
remarkable, as in water-dwelling animals it is frequently either 
absent or but slightly developed, the surrounding water answering 
all the purpose of its secretion in protecting the eye from dust, 
drying and loss of transparency of conjunctiva and cornea. The 
necessity for at least an occasional abundant lachrymal secretion in 
these animals is perhaps found in the fact that at certain times, 
especially during the breeding season, they have to leave the 
water and remain for some time on the hot sandy banks in which 
their eggs are laid. 
In the turtle the lachrymal gland lies in the posterior part of 
the orbit, that is, in the place which in human anatomy would be 
spoken of as its outer portion. It is covered and protected by the 
post frontal bone which contributes so largely to the formation of 
the false roof of the cranium found in this genus and in Chelydra. 
The gland is about three times the size of the globe of the eye ; it 
is composed of numerous closely-packed lobules of an irregularly 
flattened cleft and indented conical form, the apices of the lobules 
all converging to the central duct. Each lobule is exceedingly 
firm in texture, and on examining a thin section under the 
microscope it is seen to consist of a central core of dense connective 
tissue in which lie the larger branches of the duct, blood- 
vessels, &c. The duct is lined by columnar epithelium lying on 
a layer of superposed smaller cells. From the duct proceeds, 
directly outwards, tubular acini, which repeatedly branch and be- 
come reduced in size as they pass to the surface of the lobules. 
These acini are lined by a single layer of a most remarkable 
variety of columnar epithelium, the cells being in no place in 
contact with one another, but separated by a clear space, each cell 
having also deep grooves running along its sides, and at its fixed 
end being attached by numerous delicate root-like processes. A 
section that grazes the surface of an acinus will accordingly show 
a number of dots corresponding with the transverse sections of 
these root-like processes ; if it be a little deeper each cell will appear 
like a minute star ; whereas if the centre of the acinus be cut 
through, a true side view of the cells will be obtained, the entire 
section presenting an appearance of great beauty. 
It seems possible that this channelled condition of the epithelium 
may serve the purpose of increasing the surface from which the 
secretion may be poured out. 
