OF NON-VASCULAR ANIMAL TISSUES. 
181 
sclerotic conjunctiva upon the cornea, from injections. The fine twigs of the arteries 
of the sclerotic conjunctiva unite together around the margin of the cornea into a 
vascular wreath or circle. From these there arise very numerous branches, which 
run from the circumference towards the centre of the cornea, and in their course 
make two or three subdivisions. Their ends bend distinctly inwards, and appear to 
penetrate the proper substance of the cornea* * * § .” 
Mr. Tyrrell. “ I have been thus satisfied that the vascular organization of the 
cornea is principally derived from the conjunctiva, and little, if at all, from the scle- 
rotic vessels'!'.” 
Mr. Wardrop. “ It (the cornea) is also nourished by the same vessels which sup- 
ply the conjunctiva^:.” 
There is very considerable difficulty in making a complete injection of the vessels, 
which have the function of supplying the cornea with a nutritive fluid §. 
The vascular system of the cornea resembles that of articular cartilage, in consist- 
ing of two sets of vessels, one of which is devoted to the supply of its substance, and 
which is in contact with its margin where it is attached to the sclerotic ; the other 
supplies its free or mucous surface, the circumference of which it overlaps. 
In an eye which is injected with tolerable success, the white sclerotic membrane 
will be observed to be traversed by two sets of vessels. One of these consists of 
small and numerous branches, which have a straight direction towards the circum- 
ference of the cornea. These are the ultimate branches of the sclerotic arteries which 
course towards the cornea. The other set of vessels is composed of the large and 
tortuous trunks which are seen with ease by the naked eye ; these are the sclerotic 
veins, which take a retrograde course to the arteries just alluded to, and become 
gradually larger as they get more remote from the cornea; these sclerotic veins re- 
turn the blood devoted to the nutrition of the cornea. 
Upon examining the arteries with a magnifying glass, they will be found, at the 
circumference of the cornea, to terminate in two sets of vessels ; of these, one is 
superficial, and consists of delicate branches which pass inwards over the surface of 
the cornea, between it and its mucous covering, and are analogous to the vessels 
of joints which pass between the articular cartilage and the synovial membrane. 
The other set of vessels, in which the sclerotic arteries terminate, are much larger 
than those just noticed, and are more like the continuation of their trunks ; these, at 
the circumference of the cornea, pass into the substance of the sclerotic, where they 
come in contact with the attached margin of the cornea. 
* Mr. Wharton Jones, Medical Gazette, vol. xxiii. p. 593. 
f Medical and Cliirurgical Transactions, vol. xxi. p. 17. 
+ Tire Morbid Anatomy of the Human Eye. 
§ I have made more than fifty injections of the eye, and I possess only three specimens in which the vessels 
alluded to are successfully filled. 
2 B 2 
