THE FASCINATION OF LIGHT 323 



luminous marine fishes, of which many species are 

 known to exist), it will suffice to mention one or 

 two common birds, which may be studied by any- 

 one who will take the trouble to look for them in 

 their proper haunts. For instance, the Heron and 

 the Kingfisher. 



Many years ago the late Edward Jesse, in the 

 second series of his Gleanings in Natural History, 

 wrote (p. 285) : " It has been supposed that a 

 light is emitted by Herons from their breast as they 

 stand in the water of an evening waiting for fish. 

 I should like to be assured of the accuracy of this 

 supposition." A phosphorescent light is, of course, 

 intended. Strange to say, hardly any information 

 on this point is forthcoming, notwithstanding the 

 number of books and articles which have been 

 published from time to time on the subject of 

 phosphorescence in animals and plants, the animals 

 dealt with being chiefly fishes, marine invertebrates, 

 and insects. Now it must have been often a matter 

 for speculation with naturalists how the Heron, 

 when fishing on a dark evening, especially during 

 the winter months and in the bed of a stream over- 

 hung with bushes, contrives to see and stab with 

 his long beak the fish he so patiently waits for. 

 Can there be any truth in the supposition that 

 certain portions of the plumage are luminous at 

 night, whereby the bird is enabled to illumine the 

 water over a small area in front of it sufficiently to 

 see any fish within that area, and to use the light 

 as a lure? If so, the question arises what part, or 

 parts, of the plumage are likely to harbour phos- 



