﻿Anmial Nature of Eozo'dn Canadense. 73 



It has been pretended that the veins of chrysotile, when 

 parallel to the laminie, cannot be distinguished from 

 the minute tubuli terminating on the surfaces of the 

 iamin*. I feel confident, however, that no microscopist 

 who has seen both, under proper conditions of preservation 

 and study, could confound them. The fibres of chrysotile 

 are closely appressed parallel prisms, with the optical 

 properties of serpentine. The best preserved specimens 

 of the ", proper wall" contain no serpentine, but -are 

 composed of calcite with extremely minute parallel 

 cylinders of dolomite about five to ten microms. in 

 diameter, and separated by spaces greater than their own 

 diameter (see my comparative figure, " Dawn of Life," 

 p. 106 ; also Figs. 5. 6). In the rare cases where the 

 cylinders are filled with serpentine they are, of course, still 

 more distinct and beautiful. At the same time I do not 

 doubt that observers who have not seen the true tubula- 

 tion may have been misled by chrysotile veins when these 

 fringe the laminiie. Mobius, for instance, figures the true 

 and false structure as if they were the same. 



Protest should here be made against that mode of treat- 

 ing ancient fossils which regards the most obscure or 

 defaced specimens as typical, and those better preserved 

 as mere accidents of mineral structure. In Tertiary 

 Nummulites injected with glauconite, it is rare to find 

 the tubuli perfectly filled, except in tufts here and there, 

 yet no one doubts that these patches represent a con- 

 tinuous structure. 



I have remarked on previous occasions that the calcite 

 constituting the laminae of Eozooon often has a minutely 

 granular appearance, different from that of the surround- 

 ing limestone. This is, I presume, the " dusty " appear- 

 ance referred to by Dr. Bonney. Under a high power 

 it resolves itself into extremely minute dots or flocculi, 

 somewhat uniformly diffused. Whether these dots are 

 particles of carbon, iron, apatite, or siliceous matter, or 



