WHAT MAY BE LEARNED FROM EOZOON 151 



Tertiary fossil woods retaining perfectly their most minute struc- 

 tures, yet entirely replaced by silica, so that not a particle of 

 the original wood remains. 



The above considerations as to mode of preservation of 

 Eozoon concur with those in the previous chapter in showing 

 its oceanic character, if really a fossil ; but the ocean of the 

 Eozoic period may not have been so deep as at present, and its 

 waters were probably warm and well stocked with mineral 

 matters derived from the newly formed land, or from hot 

 springs in its own bottom. On this point the interesting in- 

 vestigations of Dr. Hunt with reference to the chemical con- 

 ditions of the Silurian seas allow us to suppose that the Lau- 

 rentian ocean may have been much more richly stored, more 

 especially with salts of lime and magnesia, than that of subse- 

 quent times. Hence the conditions of warmth, light, and nutri- 

 ment required by such gigantic Protozoans would all be present, 

 and hence, also, no doubt, some of the peculiarities of their 

 mineralization. 



I desire by the above statement of facts to show, on the one 

 hand, that the study of Eozoon, regarded as probably an ancient 

 form of marine life, aids us in understanding other ancient 

 fossils, and their manner of preservation ; and on the other hand, 

 that those who deny the organic origin of Eozoon place us in 

 the position of being unable, in any rational manner, to account 

 for these forms, so characteristic of the Laurentian limestones, 

 and set at naught the fair conclusions deducible from the mode 

 of preservation of fossils in the later formations. The evidence 

 of organic origin is perhaps not conclusive, and in the present 

 state of knowledge it is certain to be met with much scepticism, 

 more especially by certain classes of specialists, whose grasp of 

 knowledge is not sufficiently wide to cover, on the one hand, 

 fossilization and metamorphism, and on the other, to under- 

 stand the lower forms of life. It may, however, be sufficient to 

 qualify us in turning our thoughts for a few moments to con- 



