52 THE LESSON OF EVOLUTION 



favouring the view that it was a Foraminifer, after- 

 wards changed his opinion. Other specimens from 

 Bavaria, Bohemia, Ireland, Scandinavia, and Brazil, 

 which at first were supposed to be Eozoon, are now 

 acknowledged to be inorganic ; and somewhat similar 

 structures have been found in a calcareous veinstone 

 in eastern Massachusetts and in an altered limestone 

 from Vesuvius. 



It is, however, chiefly the position in which Eozoon 

 is found which makes it impossible to believe that it 

 is of organic origin. Professor Bonney has pointed 

 out that the original Eozoon occurs on the periphery 

 of blocks of a variety of pyroxene called Malacolite, 

 surrounded by crystalline limestone, and that it is 

 formed by grains of this Malacolite, generally altered 

 into serpentine, scattered through the limestone. 1 On 

 the organic hypothesis these blocks of pyroxene were 

 the rocks in the ocean on which Eozoon grew ; but 

 evidently this cannot be the case, for the blocks are 

 segregation masses, and were, no doubt, formed at the 

 same time as the grains of serpentine which are sup- 

 posed to infiltrate the organism. 



Also, the supposed canals are sometimes filled with 

 dolomite, a mineral which is usually altered calcite, and 

 is rarely deposited in cavities of unaltered calcite. 



The great thickness and extent of the limestones 

 with which Eozoon is associated forbid the idea that 

 they are entirely the result of hydrothermal action on 

 lime-bearing silicates ; but it does not necessarily 

 follow that they must be organic. Also, we can 

 hardly suppose the large quantities of graphite found 

 in these limestones to be organically derived ; for, if 



1 Geological Magazine, 1895, p. 292. 



