Jeffries.] 208 [February 2, 



A great number of Arachnidae, mostly of small size, were noticed 

 under the same circumstances, and appeared to represent many- 

 species. 



He was in pursuit of the aberrant forms, Boreus and Chionea, but 

 several hours of careful search failed to reveal any specimens of either. 



February 2, 1870. 



Vice President Dr. C. T. Jackson in the chair. Thirty three 

 persons present. 



Dr. B. Joy Jeffries stated that, as at different times during 

 the past three years he had had occasion to call the attention 

 of the Society to the physiology of accommodation in man 

 and other animals, including birds, he would ask to be 

 allowed to make a few remarks on a special part of the eye 

 which is interested in, and may be employed in, accommoda- 

 tion. 



He illustrated his remarks by a series of pictures and diagrams 

 representing sections of the human eye and of a number of different 

 animals, made through the ciliary muscle and the adjacent parts of 

 the sclerotic, cornea and iris. From dissections made by many ana- 

 tomists, and the special studies of several physiologists, it resulted that 

 the space in the eye hitherto known as the canal of Fontana, who 

 first described it in 1778, is now proved not to be a canal with walls, 

 but rather a triangular space between the ciliary muscle, iris, and 

 sclerotic or cornea, filled by a sort of mesh work attaching the iris to 

 the last named membrane. This mesh work is cut off from the aque- 

 ous humor. It constitutes the ligamentum pectinatum iridis, and is 

 quite distinct from the circular venous sinus in the sclerotic just 

 outside of it, which has apparently sometimes been mistaken for it. 

 Dr. Jeffries discussed the question as to whether it took part in the 

 accommodation of the eye, if not in man where it seemingly could 

 not, in the lower animals where its size increases with the decrease 

 of the ciliary muscle. He remarked that our present knowledge of it 

 is due to the recent researches of Drs, Iwanoff and Rollett. 



