LECTURES. 51 
inside their mouths; and in the young Ascidian inside the brain. 
Then the eyes of fishes, birds and serpents were described. Next 
considerable reference was made to the third eye of many lizards— 
an eye not readily seen, unless one knew where and how to look for 
it. Its unexpected connection with the Pineal gland of the brain 
was then referred to—a discovery only about seven years old—from 
which we may assume that this long puzzling Pineal gland is only 
the undeveloped stalk or nerve of a third eye, with which we might 
have been provided had it been so ordered. 
Finally the exactions in reference to eyesight of the Army and 
other Examining Boards were spoken about. No candidate can be 
accepted who has less than one-sixth of the natural sharpness of 
vision, as tested by types twenty feet away; but given that degree of 
vision he will be accepted, if with glasses one eye shall attain to 
normal vision and the other one to read small print at his own 
distance without glasses, and that he shall be able to distinguish the 
principal colours, and that he does not squint. For the Navy, 
no imperfections are permitted. For the Marines none beyond those 
that can be corrected by the weak lenses known as + or— ID 
(= 4oin). 
The lecture closed with the remarkable statement that whereas 
33 per cent. of boys are colour-blind, the number of colour-blind 
girls is only one-twentieth of that percentage. 
At the close of the lecture the Principal proposed a most hearty 
vote of thanks be given to Dr. Ferguson. This was carried by 
acclamation. 
