Answers to Queries. 
252.—Pineal Gland.—The pineal gland is a small gland, 
situated in the higher vertebrates, at the lower surface of the brain. 
It was a standing puzzle to anatomists, as its function was 
absolutely unknown. Feeling they must assign some use to this 
mysterious appendage, some wise men declared it must be the seat 
of the soul. In the lower vertebrates, such as reptiles and 
amphibia, the cerebral lobes do not cover the pineal gland, and 
it is just under the parietal suture—viz., that portion of the skull 
where the cranial bones are not completely closed in new-born 
children. A German and an English scientist, working indepen- 
dently, found that in the two species of lizards they were 
examining (Hatteria and Varanas), the pineal gland was connected 
with a perfectly formed eye in fact that it was an offic lobe. This 
eye is provided with a richly branched blood-vessel and nerves, 
and has its lens and layer of rods and cones of the retina, and in 
Varanus there is a modified transparent scale to act as a cornea. 
In embryonic amphibians the eye is still connected with the pineal 
nerve, but in adult frogs and toads the nerve strands become 
atrophied. But in the amphibia the pineal eye, is found just 
outside the skull, pointing to a greater functional development in 
some remote ancestors than obtains in the reptilia. In point of 
fact, in the Labyrinthodonts the parietal opening in the skull was 
very large, showing roughness for the attachment of muscles, and 
pointing to the conclusion that the pineal eye was’ functional in 
these animals, and that it was “‘ pre-eminently a sense organ of 
pre-tertiary periods.” 
The pineal eye is of zzvertebrate type, and thereby carries one 
back to an antiquity, in which the Labyrinthodont seems but a 
creature of yesterday. A. BopiIncron, Vancouver. 
337.—Etching on Glass.—There are three ways of doing this: 
(1) With hydrofluoric acid. Solution commonly called fluoric 
acid. (2) With hydrofluoric acid vapour. (3) With the sand- 
blast. Methods Nos. 1 and 2 require the article to be previously 
coated with either wax or a mixture of wax and Brunswick black 
dissolved in turpentine. This having been allowed to set, the 
design is etched through the wax with a needle or graver, or if the 
design be one requiring large spaces to be etched, it is preferable 
to cover the glass only over those parts with the wax, etc., which 
are not required to be attacked by the acid. Having thus pre- 
pared the glass, cover it with a solution of hydrofluoric acid, taking 
the precaution to keep all clear spaces well covered with the 
liquid, which can easily be done by means of a large camel’s-hair 
