134 History of Luminescence 



logical processes, involving decompositions of various kinds, more 

 specifically to the activity of yeast and other microorganisms (see 

 Chapter XIV) . The late eighteenth-century view, which still at- 

 tributed the process of fermentation to movement of the particles 

 of one substance affecting another, lasted well into the eighteenth 

 century, and indeed, traces of the idea in chemical thought persisted 

 after ferinents became definite chemical entities. With the discovery 

 in 1887 of an enzyme, luciferase, responsible for light emission of 

 plants and animals, perhaps we should not criticize too strongly the 

 early use of the word " fermentation " to explain the light of rotten 

 wood, long dead fish, and glowworms. 



Miscellaneous Writers 



Since no comprehensive book on luminescence appeared at the 

 end of the seventeenth century, ideas regarding luminescence must 

 be obtained from the writings of various well-known men, chiefly 

 members of the Royal Society or the French Academy. Plot, Casati, 

 Bottone, Lemery, Rohault, and Newton have all presented their 

 views more or less casually in memoirs or in books dealing with 

 other subjects. These men represent quite different approaches to 

 the subject and their theories are correspondingly diverse, but repre- 

 sentative of late seventeenth-century thought. Their statements illus- 

 trate a point made earlier in this chapter— the value of the scientific 

 society in stimulating the acquisition of knowledge. 



ROBERT PLOT 



Robert Plot, L.L.D. (1640-1696), keeper of the Ashmolean Mu- 

 seum and professor of chemistry in the University of Oxford, was a 

 contemporary of Boyle and Hooke. His interest in luminescence 

 apparently arose from an account of luminous turf, recorded in his 

 Natural History of Staffordshire (London, 1686, Chap. Ill, p. 115). 

 He wrote a vivid description of horses' hooves, which " fling up 

 so much fire " from the peaty ground of a moor near Berefford over 

 which they passed. The display of luminescence, as pointed out 

 in Chapter XVI, was undoubtedly due to luminous earthworms 

 living in the peat, but it stimulated Plot to discourse on " the things 

 there are beside fire . . . that give any light " and " whether the 

 shining of the earths and mud above mentioned, may not be reduced 

 to some one, or more of them," He divided " luciferous bodies, that 

 send forth a light and yet have nothing of the nature of fire " into 

 " animate, and others inanimate ": 



