i 
PREFACE. ix 
nected with phosphoric phenomena, or the spon- 
taneous emission of light by natural or artificial 
substances, as well as by living and dead organic 
bodies, these phenomena must be studied in the 
whole domain of Nature—in the mineral, in the 
vegetable, and in the animal world. I have there- 
fore brought forward what I know on the subject, 
with regard to mineral substances, and have ex- 
tended my investigations to vegetables, to animals, 
and to organic matter deprived of life. The phe- 
nomenon of Phosphorescence will thus have been 
studied simultaneously throughout Nature, and 
this is, to my knowledge, the first time that the 
interesting series of facts I have consigned to 
these pages have been looked upon as constitu- 
ting a whole. 
Phosphorescent properties, although developed 
to a prodigious degree in the insect world, are 
found nevertheless to exist in numerous other ani- 
mals, in many plants, and also in certain minerals 
and chemical products. They pertain at once to 
the science of chemistry and physics, as well as to 
botany and physiology. Those who possess a 
profound knowledge of these different branches of 
natural history, can alone hope to arrive at the 
