1872. J Dr. K. J. Lee on the Sense of Sight in Birds. 



353 



interesting work on this subject Mr. Tegetmeier gives his reasons for con- 

 cluding that " Homing," as it is termed in the Antwerp pigeon, is not the 

 result of "instinct," but of " observation." These pigeons require to be 

 trained stage by stage, or they are certain to be lost. The best of them 

 refuse to fly in a fog or in the dark. They crave in new localities some 

 known landmark ; and hence their gradually increasing gyrations, until 

 having descried some familiar object, they recollect their route and fly 

 straight ahead. The objection that no pigeon can possibly see for two 

 hundred miles ahead is met by the details of aeronautic experience. Mr. 

 Glaisher, half a mile aloft in air, could embrace in his " bird's-eye 

 view" the course of the Thames from the Nore to Richmond ; and Mr. 

 Wheelwright, though puzzled to account for the flying pigeons " homing" 

 across seas (as from London to Antwerp), which can offer no landmark, 

 is disposed to attribute their power of doing so to their habit of soaring 

 round, circling, and beating about until, sooner or later, they can descry 

 their familiar guide-posts. 



My own observations entirely support Mr. Tegetmeier's conclusions. 

 This part of my subject is one of general interest, and I trust that I 

 shall be pardoned for attempting to alleviate the tediousness of anatomical 

 details by this digression. 



It must clearly be understood that perfection of sight for very near ob- 

 jects is as important as very extensive range, and that the chief function of 

 the ciliary muscle is to adjust the sight for the former rather than for the 

 latter. When the eye is at rest (that is to say, when the muscle is relaxed) 

 vision of very distant objects is permitted ; and it is when the distance is 

 diminished to a very few inches, and in small species of birds to consider- 

 ably less than an inch, that the action of the muscle is exerted. 



The exact functions performed by the ciliary muscle in all those verte- 

 brata in which it exists are still undecided ; but it is not difficult to reconcile 

 the accounts which have been given by different anatomists of its structure, 

 if we are aware of the fact that the muscle does not possess the same 

 characters in all classes of animals ; indeed that it is not precisely the same 

 in those that, are very nearly allied, so that it is important, particularly in 

 the case of birds, as will be seen, to mention the species under consideration. 



It may be stated generally that in birds it is developed in a remarkable 

 degree ; in fish it is entirely wanting ; in the mammalia it varies directly in 

 proportion to the powers of sight possessed by the species, except in the 

 feline class and in those animals which enjoy the power of nocturnal 

 vision, and in which the ciliary muscle is peculiarly large and differently 

 developed from the same structure in other mammals. 



The three specimens which are to be described belong to the Eagle Owl, 

 the Egyptian Vulture, and the Buzzard. They were brought from Egypt 

 by a gentleman who shot the birds himself, and removed the eyes while 

 in the fresh state, preserving them in spirit of wine till he sent them 

 to me. 



