THE USES OF PHOSPHORESCENCE. 167 



sulphurets and sulphides, etc., and to obtain as long a phos- 

 phorescence as possible, is all I want to reduce stellar pho- 

 tography to the simplest and cheapest apparatus, and make 

 it available to every one." 



As we have seen, the light emitted by animals, plants, and 

 minerals, of whatever cause, presents much that is mysteri- 

 ous ; and the problem of animal phosphorescence would 

 seem no nearer being solved to-day than it was fifty years 

 ago. This is perhaps due to a lack of study and investiga- 

 tion. A glance at the appended bibliography shows that 

 much has been written upon the subject ; but it is only within 

 the last decade that serious work in this direction has been 

 done, typified in the superb work of Dubois, and the papers 

 and monographs of the other scientists mentioned. The 

 naturalists of the "Albatross," the government exploring- 

 steamer, are to make investigations regarding the luminosity 

 of the Pacific, during the forthcoming tour on the western 

 coast. The French Academy of Sciences offers this year a 

 prize of three thousand francs for the best paper upon animal 

 phosphorescence. From this it would appear evident that the 

 phenomenon is creating renewed or increasing interest, and 

 in the following years will be the subject of much study 

 and investigation ; and we may expect in the near future to 

 have not only its cause explained, but possibly to see a 

 practical application of its possibilities to the wants of 

 mankind. 



