352 JAMES ROLLIN SLONAKER 



In this connection I desire to thank my colleague, Dr. Wood, 

 for kind assistance rendered during the preparation of this 

 article. 



The English sparrow (Passer domesticus) has been chosen 

 because of its almost cosmopolitan distribution, its abundance, 

 and the ease with which it can be secured. 



Adult sparrows were secured alive by means of traps and were 

 confined in cages until needed. An abundance of fresh material 

 was thus secured. This also enabled* one to make various 

 observations in regard to the movements of the eyes and lids 

 and the angle of vision. To test the power of convergence, one 

 eye was removed from several birds. These experiments will 

 be described later. 



The eyes were removed immediately after death and hardened 

 in Perenyi's fluid and imbedded in celloidin. Serial sections 

 were made and stained in haematoxylin and eosin. Perenyi's 

 fluid preserved the retina in the most perfect condition of any 

 hardening fluids tried, and at the same time decalcified the bone 

 wherever present. In some cases the whole head was preserved 

 and sectioned to show the relations of the various parts. Sec- 

 tions were made in both horizontal and vertical planes parallel 

 to the axis of vision. 



To facilitate the dissection of the blood supply to the eye and 

 accessory parts fresh specimens were used. The arteries were 

 injected with carmin-gelatin and the veins with blue. The 

 binocular dissecting microscope was used in the dissection of 

 the various structures. Camera-lucida drawings were made 

 wherever possible. All other drawings were made to scale. 



THE EYEBALL 



The eye of the sparrow, as in all birds, is relatively very large. 

 When the eye is wide open, the interpalpebral space is practi- 

 cally a circle and is entirely filled by the cornea, none of the 

 sclerotic being visible. This condition prevails during the time 

 that the bird is awake, as the true lids take no part in bathing 

 the front of the eye with the lacrimal secretions. The shape and 

 size of the eye of the sparrow are quite different from that of 



