V°'- 1^^6^"^] General Notes. 81 



Eye Shine in Birds.— In a recent interesting and valuable article on 

 " Nature's Transformations at Panama " (National Geographic Magazine, 

 August, 1915, p. 176) Shiras called attention to, and gives his observa- 

 tions in studying, the glow seen at night in the eyes of various animals 

 when they are facing a bright light. 



The present writer is pleased to contribute to the literature of this sub- 

 ject an observation of iiis own. Not long ago, while motoring at night 

 through a particularly dark canyon, I noticed far ahead in the illuminated 

 road, two small glowing pink spots, which were extinguished when a bird 

 flew from the road on the near approach of the car. The bird alighted 

 again, some distance ahead in the road, when the pink points reappeared, 

 and were identified as the bird's eyes; it was shot, and proved to be a 

 Nuttall's Poorwill. This observation fits in well with those of Shii'as who 

 recorded this eye shine in Nighthawks. 



It is well here to interject the question as to whether this glow in birds' 

 eyes does come from a true tapetum lucidum, as is implied (or stated) by 

 Shiras, inasmuch as Casey Wood (a highly qualified authority on compara- 

 tive ophthalmology) says " The tapetum is absent in birds, although the 

 Ostrich has a glass-like layer in the choroid of lamellated structure capable 

 of reflecting light. This arrangement, however, is only a retino-choroidal 

 variation, and not a true tapetum " (Am. Encyclop. Ophthalmology, Vol. 

 IV, p. 2653). 



The present writer has no desire to split hairs, but merely wishes to call 

 attention to a point (one amongst hundreds) awaiting decision. It may 

 be that no bii-d has a true tapetum, or if Caprimulgine birds have not yet 

 been examined for this structxxre, it is equally possible that birds of this 

 type do have a true tapetum; all this reminds one that there is plenty of 

 material still left for original research, or to be used in corroborating or 

 disproving earUer work. — W. H. Bergtold, Denver, Colo. 



Weight and Contents of Birds' Eggs.^The following data have been 

 collected during the past two years and are here presented as there seems to 

 be but little recorded information on the subject. The eggs were weighed 

 before and soon after blowing (when thoroughly di-y). The latter weight 

 of course, represents the weight of the shell and the difference between the 

 two, the weight of the contents. The contents are also given in cubic 

 centimeters. In some cases the actual contents were measured, in others 

 the shell was filled with water and the water measured. With proper 

 instruments it would be possible to determine the specific gravity of the 

 contents of the egg. It would be interesting to learn if this would show any 

 relation between eggs of species of the same family or order. 



Only averages are given below for each set or series of eggs. 



