518 Royal Society : — 



vations, exophthalmosis being most easily produced on this animal, 

 while the eye is so transparent and the iris so close to the cornea, 

 that the circulation of the blood-globules in the vessels of the iris may 

 be observed. At the same time, beneath the iris and sclerotic may 

 be seen the ciliary processes from their origin at the ora serrata to 

 their anterior extremity, where they are seen to form a circular crown 

 with a serrated edge surrounding the crystalline lens. The vessels 

 of the cihary ligament of the choroid are likewise rendered accessible 

 to actual inspection during life. 



For the purpose of examination, the animal is secured by a few 

 turns of a band, about 1^ inch in width, passed round its body so as 

 to confine the limbs. It is then placed on a narrow slip of cork, to 

 which it is fixed by some turns of string. When steadily fixed, ex- 

 ophthalmosis is produced and maintained by passing a strong thread 

 around the shp of cork and the head of the animal close to the eye, 

 alternately in front and behind it. "When the compound microscope 

 is used, it will be found reqviisite to place the animal sidewdse, so as 

 to direct the object-glass over the bright image above mentioned, 

 which is always formed when the eye is placed before any bright 

 light. 



The author first describes the vessels of the conjunctiva over the 

 sclerotic and cornea. These vessels form a network behind and 

 before the ciliary ligament, and join into numerous small trunks 

 which unite with a circular ciliary vein running all round the ciliary 

 ligament. In the corneal conjunctiva the vessels may be traced 

 towards the summit of the cornea over the outer half of its surface, 

 and even beyond. They are seen to commence internally, as if with 

 free extremities, from whence the blood is seen circulating rapidly 

 towards the circumference of the cornea. Then large meshes soon 

 form, which become smaller as they approach the ciliary ligament, 

 where they terminate in a circular vein surrounding the cornea. The 

 rapid circulation of the blood at the apparent extremities of the ves- 

 sels over the inner parts of the cornea, indicates llieir further con- 

 tinuation inwards or below, although the author has not traced them 

 further over the cornea. 



The vessels of the anterior surface of the iris, which Dr. Waller 

 next examines, consist of arteries and veins. The former are derived 

 almost entirely from the two long ciliary arteries which arrive near the 

 outer and inner angles of the eye, their course being traced over the 

 anterior half of the sclerotic until they reach the great circumference 

 of the iris, where they each subdivide into two equal branches, one 

 inferior, the other superior, which diverge at an obtuse angle, each of 

 them running in an obhque direction towards the edge of the pupil 

 until they attain the inner third of the iris, where most of the final 

 subdivisions are bent outwards. These four oblique branches form a 

 symmetrical figure of a lozenge-shape over the iris, each branch 

 giving off internal and external twigs, the former ending in the small 

 circumference, the latter in the large circumference of the iris. The 

 course of the blood may be watched in these vessels from over the 

 sclerotic to their termination in the iris, but in general the current 



