104 



THE DAWN OP LIFE. 



need we be astonished at the fineness of the infil- 

 tration by which these minute tubes, perhaps y^^^ of 

 an inch in 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 microscope can detect. Wherever the 

 fluids of the living body can penetrate, there also mineral 



FIG, 26. Shell from a Silurian Limestone, Wales ; its cavity filled 

 with a Hydrous Silicate. 



Magnified 25 diameters. 



substances can be carried, and 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. 25 represents a micro- 

 scopic joint of a Crinoid from the Upper Silurian of 

 New Brunswick, injected with the hydrous silicate 

 already referred to, and fig. 26 shows a microscopic 



