494 History of Luminescence 



tombs." Cabanis then pointed out that the brain and nervous system 

 are particularly rich in phosphorus. Hence, 



It is the commencing decomposition of cerebral tissue, to which are due 

 those phosphoric lights which are often observed in [dissection] amphi- 

 theatres at night; and it is principally around the exposed brains or 

 their debris on the dissecting table that one notices them. A very great 

 number of observations have led me to believe that the quantity of 

 phosphorus which develops after death is proportional to the activity of 

 the nervous system during life. It appears to me that the brains of per- 

 sons dead of maladies characteristic of excess of this [nervous] activity 

 emit a light more brilliant and sparkling; those of maniacs are very 

 luminous; those with dropsy or of the "leuco-fiegmatiques " type are 

 much less so. 



In a footnote Cabanis explained further that, 



The brilliance of light from (luminous) animals is related to their vital 

 energy or to the degree of their excitation. This light is, for example, 

 more brilliant at the time of their loves. It even appears that it is 

 destined, in many species, to serve as a guide and lantern to the male 

 when he searches for the female; " elle est alors a la lettre le flambeau 

 de I'amour." 



The grandfather of Charles Darwin, Erasmus Darwin (1731- 

 1802) , botanist and poet, was rather more specific, believing that 

 oxygen combined with carbon or sulphur or phosphorus to give 

 heat, as in a dung-hill, or to give light, as in rotten wood. In his 

 Phytologia or the Philosophy of Agriculture and Gardening (Sec. X, 

 5. 1, London, 1800) , Darwin called attention to phosphorescent 

 wood so bright "as to alarm benighted passengers; which is un- 

 doubtedly owing to the phosphorus it contains, and which is at this 

 time converted into phosphoric acid." 



Antoine Francois de Fourcroy (1755-1809) , professor of chemistry 

 at the Jardin des Plantes, in his eleven-volume System des Connais- 

 sances Chemiques (Paris, 1801) , took particular pains to point out 

 that wood often becomes luminous during the course of slow putre- 

 faction and develops an odor of " des agarics et des bolets." This 

 was a happy observation, but Fourcroy did not realize the causal 

 connection between luminescence and the fungus smell, merely 

 included these peculiarities among others characteristic of " bois 

 pourri," such as the change in color, the light weight, the softness, 

 and the fact that rotten wood burned quickly without much heat. 

 Luminous wood and fungi were not definitely associated until the 

 letter of Derschau to Nees von Essenbach in 1823. 



The prize essays of Bernoulli and Link, were not primarily con- 



