146 WHAT MAY BE LEARNED FROM EOZOON 



formed in any other way. Nor need we be astonished at the 

 fineness of the infiltration by which these minute tubes, perhaps 

 Too o ^^ ^^ i^^ch ^^ diameter, are filled with mineral matter. 

 The micro-geologist well knows how, in more modern deposits, 

 the finest pores of fossils are filled, and that mineral matter in- 

 solution can penetrate the smallest openings that the micro- 

 scope can detect. Wherever the fluids of the living body can 

 penetrate, there also mineral substances can be carried, and 



Fig. 17.— Shell from a Silurian Limestone, Wales ; its cavity filled with 

 Hydrous Silicate. Magnified 25 diameters. 



this natural injection, effected under great pressure and with 

 the advantage of ample time, can surpass any of the feats of 

 the anatomical manipulator. Fig. 16 represents a microscopic 

 joint of a Crinoid from the Upper Silurian of New Brunswick, 

 injected with the hydrous silicate already referred to, and Fig, 

 17 shows a microscopic chambered or spiral shell, from a 

 Welsh Silurian limestone, with its cavities filled with a similar 

 substance. 



Taking the specimens preserved by serpentine as typical, we 

 now turn to certain other and, in some respects, less character- 



