HISTORICAL NOTES. 179 



hind, and believed in the old opinion of Beccaria, 

 Heinrich, at Nuremberg, and Pearsall, in London, 

 supported the ideas of Dessaignes. Becquerel 

 and Biot have the merit of having first studied 

 the influence of transparent screens of different 

 substances (glass, quartz, calcareous spar, etc.) in 

 promoting or extinguishing phosphorescent light 

 produced by insolation. Their experiments were 

 repeated recently by Professor Henry, of Phila- 

 delphia. The action of coloured glasses upon this 

 phenomenon had already been investigated by 

 Wilson and Beccaria. 



I shall not repeat here what I have stated in 

 other parts of this work concerning the discovery 

 of plant-phosphorescence and of light-emitting 

 animals. 



For the benefit of those who might desire to 

 consult some of the more important and original 

 documents relating to the subject of phospho- 

 rescence, I have determined to give, in an Ap- 

 pendix to this work, their titles, and the dates of 

 their publication. 



As we have already seen, the light emitted by 

 flowers is thought to be owing to electricity ; but 

 as for that which is evolved from Fungi, such as the 

 Agaric of the olive, the Rhizomorpha, etc., no idea 

 has been formed of the direct cause of the lumi- 

 nous phenomenon. 



According to Matteucci, Roberts, and De 



