48 THE DAWN OF LIFE. 



of life may be known as inhabitants of oceans vastly 

 ancient as compared with even the old Primordial 

 seas. Who knows whether even the land of the Lau- 

 rentian time may not have* been clothed with plants, 

 perhaps as much more strange and weird than those 

 of the Devonian and Carboniferous, as those of the lat- 

 ter are when compared with modern forests ? 



NOTES TO CHAPTER III. 



(A.) Sir William E. Logan on the Discovery and 

 Characters of Eozoon. 



[Journal of Geological Society, February, 1865.] 



'* In the examination of these ancient rocks, the question 

 has often naturally occurred to me, whether during these 

 remote periods, life had yet appeared on the earth. The 

 apparent absence of fossils from the highly crystalline lime- 

 stones did not seem to offer a proof in the negative, any more 

 than their undiscovered presence in newer crystalline lime- 

 stones where we have little doubt they have been obliterated 

 by metamorphic action ; while the carbon which, in the form 

 of graphite, constitutes beds, or is disseminated through the 

 calcareous or siliceous strata of the Laurentian series, seems 

 to be an evidence of the existence of vegetation, since no one 

 disputes the organic character of this mineral in more recent 

 rocks. My colleague. Dr. T. Sterry Hunt, has argued for the 

 existence of organic matters at the earth's surface during the 

 Laurentian period from the presence of great beds of iron ore, 

 and from the occurrence of metallic sulphurets ; * and finally, 

 the evidence was strengthened by the discovery of supposed 

 organic forms. These were first brought to me, in October, 

 1858, by Mr. J. McMuUen, then attached as an explorer to the 



* Quarterly Journal of the Geological Society, xv. , 493. 



