304 Dr. Jacob’s account of 
called, the black pigment is found resting upon, and at- 
tached to, a soft friable thick fleecy structure, which can only 
be detached in small portions, as it breaks when turned down 
in large quantity. Or if the cornea and iris be removed 
anteriorly, and the vitreous humor and lens withdrawn, the 
retina may be pulled from the membrane, which remains 
attached to the choroid coat, its inner surface not tinged 
by the black pigment, but presenting a clear white, not un- 
aptly compared by Haller to snow. 
Besides being connected to the retina, I find that the mem- 
brane is also attached to the choroid coat, apparently by fine 
cellular substance and vessels ; but its connection with the 
retina being stronger, it generally remains attached to that 
membrane, though small portions are sometimes pulled off' 
with the choroid coat. From this fact I think it follows, that 
the accounts hitherto given of the anatomy of these parts, 
are incorrect. The best anatomists* describe the external 
surface of the retina as being merely in contact with the cho- 
roid coat, as the internal with the vitreous humor, but both 
totally unconnected by cellular membrane, or vessels, and 
even having a fluid secreted between them : some indeed 
speak loosely and generally of vessels passing from the cho- 
roid to the retina ; but obviously not from actual observation, 
as I believe no one has ever seen vessels passing from the 
one membrane to the other. My observations lead me to con- 
clude, that wherever the different parts of the eye are in 
* See Haller, Elem. Phys. T. v. lib. xvi. sect. ii. Zinn. cap. ii. sect. i. § ii, 
Boyer, Anat. T. iv. p. 113. Sab atier, T. ii. p. 70. Bich at, Anat. Descr. T. ii- 
p.447. Cuvi er, Lefons d’Anat. Comp. T. ii. p. 418, Charlss Bell, Anat. 
vol. iii. p. 51. Rises, Mem. de la. Soc. Med. d’Emulation, T. viii. p» 633. 
