35S Dr Knox on the Foramen centrale of the Retina . 
In the annexed sketch, the 
black lines represent the form 
as given by Mr Harvey, and 
the dotted lines the alterations 
which X venture to propose. 
It will here be seen that the 
after-gun on the broadside has its full effect. The gun at the 
salient has fully as great a range as the quarter-gallery gun on 
the round stern ; and there will be more room for the men to 
fight their guns. 
Art. XXVII. — On the Discovery of the Foramen centrale of the 
Retina in the Eyes of Reptiles. By Dr Knox. 
All anatomists are aware, that, previous to the discovery of 
the foramen centrale in the human retina, by Dr Soemmering, 
this important structure had completely eluded observation. 
Since that time, the most active researches have been made into 
the structure of the eye-ball, in every class of animals; but the 
only additional fact which has, in consequence, been added to the 
discovery of Soemmering, has been, that the foramen centrale js 
not confined to man, but extended to several of the quadruma- 
nous animals ; and, more particularly, to the real apes of the Old 
and New Continent. The more obvious conclusion, drawn from 
these facts, and which, perhaps, was warranted by the state of 
knowledge at the time, was, that the foramen centrale , the ac- 
companying fold of the retina, and the yellow spot, were simply 
proofs of a high degree of organization in man, and that their 
reproduction in apes, was owing to the general resemblance 
these animals bore to the human species. But the very singular 
and unexpected discovery which has some time ago been commu- 
nicated to us by Dr Knox, entirely refutes these suppositions, 
and will compel physiologists to look for other explanations, and 
may ultimately change several prevailing notions relative to the 
theory of vision. 
The full details of this discovery, are intended for the Trans- 
actions of the Wernerian Society of Edinburgh. In the mean 
time, we may state, that the reptiles in whose eyes the foramen 
centrale , and fold of the retina, have been observed, belong to the 
f class Lizards; such as the Laccrla scutata, superciliosa, Calotes* 
