No. 3.] PHOSPHORESCENT ORGANS. 687 



easy to free the lens from the surrounding tissue and to examine 

 it directly. When thus freed and examined in normal saline, I 

 have found by rough estimates that it condenses sunlight to a 

 bright point a distance back of the lens of from one-fourth to 

 one-half its diameter. I regret that I have been unable to make 

 precise physical measurements. 



The literature on the histological structure of known phos- 

 phorescent organs of fishes is rather meager and unsatisfactory. 

 Von Lendenfeld describes twelve classes of phosphorescent 

 organs from deep-sea fishes collected by the Challenger expe- 

 dition. All of these, however, are greater or less modifications 

 of one type. This type includes, according to von Lendenfeld's 

 views, three essential parts, i.e., a gland, phosphorescent cells, 

 and a local ganglion. These parts may have added a reflector, 

 a pigment layer, or both ; and all these may be simple or com- 

 pounded in various ways, giving rise to the twelve classes. 

 Blood vessels and nerves are distributed to the glandular 

 portion. Of the twelve classes direct ocular proof is given 

 for one, i.e., ocellar organs of Scopelus which were observed 

 by Willemoes Suhm at night to shine " like a star in the net." 

 Von Lendenfeld says that the gland produces a secretion, and 

 he supposes the light or phosphorescence to be produced either 

 by the " burning or consuming " of this secretion by the phos- 

 phorescent cells, or else by some substance produced by the 

 phosphorescent cells. Furthermore, he says that the phos- 

 phorescent cells act at the " will of the fish " and are excited 

 to action by the local ganglion. 



Some of these statements and conclusions seem insufficiently 

 grounded, as, for example, the supposed action of the phos- 

 phorescent cells, and especially the control of the ganglion 

 over them. In the first place, the relation between the ganglion 

 and the central nervous system in the forms described by von 

 Lendenfeld is very obscure, and the structure described as a 

 ganglion, to judge from the figures and the text descriptions, 

 may be wrongly identified. At least it is scarcely safe to 

 ascribe ganglionic function to a group of adult cells so poorly 

 preserved that only nuclei are to be distinguished. In the 

 second place, no structural character is shown to belong to the 



