462 Proceedings of the 



the hot sun, and kept it damp with sea-water ; and, although 

 the plant was far gone in decay, and the stone " not prepared," 

 as well as too pale and siliceous, a faint impress was made, 

 distinct enough to show that with better materials success 

 would be certain. I have since ascertained that one of the 

 fair algologists of Pomona was long ago aware of these 

 markings, and, with the splendid materials there, had fully 

 succeeded in getting them delineated in the way that I tried. 

 We know that, as well as land-plants, sea-plants also existed 

 in the Lower Old Red periods ; plants, principally of the sea, 

 were in the Silurian times ; and, as tides ebbed and flowed 

 then, and the sun shone as now, why might not the algae be 

 cast on their exposed and ripple- marked rocks, and their like- 

 ness imprinted through a Ralfsia by the ancient Desmarestias, 

 and that, too, indelibly, before the next flowing tide swept 

 away the type, and left no trace of organic matter behind 1 

 I wish it most distinctly to be understood^ that I do not insist 

 on claiming all dendritical markings on and in rocks for the 

 botanist ; for I know that some of the doubtful markings are 

 caused by infiltration, — very many by the sportive arbo- 

 rescent forms of minerals. Add to these the markings from 

 the crawling of Crustacea, the wriggling of the Annelides, 

 and the tracks of the vegetable feeding Mollusca, all playing 

 their part in the puzzling drama. I could enumerate very 

 many things of this kind, — one observed on last New Year's 

 Day, when I saw the animal at work painting. I must, how- 

 ever, after acknowledging all this, and after striking the 

 balance, still think there is a probability that the printing 

 process had thrown off the greatest number. I have delayed 

 sending this to you, in the hope of finding some notice of a 

 like process beyond the very short one I sent to the meeting 

 of the British Association for the Advancement of Science at 

 the time of the discovery, but have never been able to find a 

 word. I therefore now venture to trouble you, in the hope 

 that it will become more widely known, and the means of show- 

 ing that it is going on in different parts of the globe. 



[Mr Alexander Bryson remarked, that this was indeed the 

 first example of Natural Photography which had been recorded ; 



