WRIGHT— RECENT SPECTROSCOPIC OBSERVATIONS. 531 



energy requisite for the production of this spectrum might be pro- 

 vided by an electric field. Interpreted through the medium of 

 Bohr's very convenient, but equally myterious conception, this con- 

 tinuous spectrum indicates for the planetary nebulae themselves a 

 degree of temperature, or electrical excitation, comparable with 

 that found to exist in their nuclei, and in other intensely radiating 

 stars. 



