^CHAPTER y. 



THE PRESERVATION OP EOZOON. 



^ERHAPS nothing excites more scepticism as to this 

 mcient fossil than the prejudice existing* among 

 Ideologists that no organism can be preserved in rocks 

 highly metamorphic as those of the Laurentian 

 jries. I call this a prejudice_, because any one who 

 lakes the microscopic structure of rocks and fossils 

 special study, soon learns that fossils undergo the 

 lost remarkable and complete chemical changes 

 without losing their minute structure, and that cal- 

 ireous rocks if once fossiliferous are hardly ever 

 lo much altered as to lose all trace of the organisms 

 rhich they contained, while it is a most common occur- 

 ence to find highly crystalline rocks of this kind 

 ibounding in fossils preserved as to their minute 

 Jtructure. 

 Let us, however, look at the precise conditions 

 ider which this takes place. 



When calcareous fossils of irregular surface and 

 )orous or cellular texture, such as Eozoon was or 

 jorals were and are, become imbedded in clay, marl, 

 )r other soft sediment, they can be washed out and 

 recovered in a condition similar to that of recent 



