390 The Action of Plants on a Photographic Plate in the Dark. 



Figs. 12 and 13, Plate 21, are from the leaf itself, black currant, and figs. 14 

 and 15 are pictures of the same leaf, but are from the paper between which it 

 was squeezed. As further illustrating the nature of the pictures obtainable 

 by these processes, fig. 16 shows the front and back of a beech leaf taken 

 direct from the leaf. Ferns and mosses also give interesting results, but 

 these will not be dealt with in the present communication. 



The above investigation has been carried out in the Davy-Faraday 

 laboratory, and my thanks are due to the managers of the Eoyal Institution 

 for the use of their laboratory. I am also much indebted to my assistant, 

 Mr. 0. F. Bloch, who has been of much help to me, and has made all the 

 photographic pictures for the illustrations. 



