PREFACE. 



IX 



does not appear to consume, and without perceptible heat exists 

 where ordinary combustion is impossible. 



From the nature of the subject, it is evident that illustrations 

 of the phosphorescence of marine animals must be more or less 

 conjectural ; and those given, representing over fifty luminous 

 forms, show as nearly as possible the probable effect produced. 

 As this work is scientific only so far as to secure accuracy, some 

 technical details have been omitted. To compensate in a measure, 

 I have appended a fairly complete bibliography of most important 

 monographs and papers on the subject, which may be of value to 

 those who wish to pursue the subject in its technical relations. 



To render the work as popular as possible, certain systematic 

 portions necessary to the student are placed in an appendix, and 

 referred to by number. The whole work is also thoroughly indexed. 



While the chief feature of the volume embraces the phosphores- 

 cence of animals, it has been deemed advisable to include reference 

 to luminous plants, minerals, and certain atmospheric phenomena, 

 which, if not strictly comprehended under our title, will perhaps 

 not be considered entirely foreign nor uninteresting in this con- 

 nection. 



It is my agreeable duty to acknowledge here the courtesy and 

 kindly attentions received from M. Raphael Dubois of the Zoologi- 

 cal Society of France; Professor H. Filhol ; Professor H. H. 

 Giglioli, Director of the Zoological Institute of Florence, Italy ; 

 Professor Carlo Emery of the University of Bologna, Italy ; and 

 M. Zenger of Prague, Hungary, who generously forwarded for my 

 use their most recent papers on the subject of phosphorescence. 



I have also to name with thanks for similar favors Dr. Gunther, 

 keeper of the British Museum, and acknowledge the value of con- 

 tributions from the works of M. Quatrefages of the Institute of 



C. F. H. 

 PASADENA, CAL., July, 1887. 



