1873.] Dr. R. J. Lee on the Sense of Sight in Birds. 107 



The accompanying solar profiles are copies of drawings made, on the 

 dates stated, by means of the new method, which were exhibited by the 

 authors at the Meeting. 



[Since reading the above paper, it has come to our knowledge that 

 Zollner had conceived the same idea unknown to us, but had rejected it. 

 Prof. Wenlock in America has tried a similar arrangement, but without 

 success. — J.N. L., Gc. M.S., January 17, 1873.] 



II. "Further Remarks on the Sense of Sight in Birds." By Robert 

 James Lee, M.A., M.D. Communicated by Robert Lee, 

 M.D., F.R.S. Received October 14, 1872. 



It was the object of my last communication to show the necessity for 

 more extensive researches into the differences of certain structures in the 

 eyes of birds in order to arrive at satisfactory conclusions regarding their 

 functions, which are still undecided by anatomists. It also appeared to 

 me to be desirable and interesting to examine the different degrees of 

 development which characterize those structures in different species of 

 birds, as they seemed to afford an explanation of the remarkable powers 

 of vision which most birds possess. 



It would be premature to enter upon general deductions until the data 

 we possess are more numerous and the anatomical details are generally 

 allowed to be correct. 



Since my last communication it has been my privilege to receive much 

 assistance and valuable information from Mr. Hulke, who has directed 

 considerable attention to the structure of the ciliary muscle in birds. 



It appears to me impossible to reconcile the various opinions which 

 Briicke, Cramer, Donders, and particularly Heinrich Miiller entertain on 

 anatomical details, except on the supposition that the exact species of 

 bird has not been considered of sufficient importance to the question, also 

 that the particular method of dissection or preparation may have been 

 the cause of a different appearance in the minute structures. In my own 

 experience I have often found that singular differences are produced by 

 the method of preparation ; and it has usually been necessary, where there 

 was any doubt, from the eye having been preserved for some time, to 

 wait till a fresh specimen could be obtained. 



In order to show the different degrees of development of the ciliary 

 muscle, a short Table has been drawn up, containing those specimens 

 which have been examined with most attention. For the present I shall 

 consider the ciliary muscle as a simple structure for the production of 

 one effect, whatever minute differences may exist in the internal arrange- 

 ment of its fibres. 



The second Table may be regarded as a continuation of that com- 

 menced in my last communication, and is intended to furnish certain data 

 which are necessary for the determination of the visual powers in various 

 species of birds, 



