PREFACE 



BioLUMiNEscENCE, the productioii of light by animals 

 and plants, has always excited the admiration of the lay- 

 man and the wonder of the scientist. It is not surprising 

 that an enormous literature dealing with the, subject has 

 grown up. A large part of this literature, however, is 

 made up merely of reports that a certain animal is lumi- 

 nous, or records of especially brilliant phosphorescence of 

 the sea. Among those who have inquired somewhat more 

 carefully into the nature and causes of light production 

 may be mentioned the names of Beijerinck, R. Boyle, 

 Dahlgren, Dubois, Ehrenberg, Krukenberg, Mangold, 

 McDermott, Molisch, Panceri, Pfliiger, Phipson, Quatre- 

 fages, Spallanzani, and Trojan. Several of these men 

 have written comprehensive monographs on the subject. 



It is not the purpose of this book to deal with every 

 phase of bioluminescence. Volumes could be written on 

 the evolutionary side of the problem and the structure and 

 uses of luminous organs. These questions can only be 

 touched upon. Neither is it my purpose to discuss the 

 ultimate cause of the light, whether due to vibration of 

 electrons or to other causes. That problem must be left 

 to the physicist, although it is highly probable that a study 

 of animal light will give important information regarding 

 the nature of light in general, and no theory of light can 

 be adequate which fails to take into account the extraordi- 

 nary powers of luminous animals. 



We shall be concerned largely with the physical char- 

 acteristics of animal light and the chemical processes 



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