1896.] Fossils and Fossilization. 911 
would seem reasonable to expect a plentiful production of 
humic acid and its allied compounds under these circum- 
stances, and if, as Julien asserts, these acids attack the phos- 
phates of alkaline earths (phosphates of alumina lime and 
magnesia), the preservation of the moa bones appears either 
exceptional or contradictory. 
In this connection it must be remembered that in all such 
vegetable infusions a considerable amount of tannin must 
accumulate, and its astringent action upon the gelatine of bone 
has a tendency to protect the bone along the interior walls of 
its cavities and canals. Lyell is at some pains to illustrate, in 
his Principles, Vol. II, pp. 508-510, the preservative properties 
of peat, but these illustrations relate more to its antiseptic 
properties for the preservation of animal tissues. Thus, in a 
peat-moss in the Isle of Axholm, Lincolnshire, Scotland, a 
body of a woman was preserved six feet below the surface ; 
bodies of two persons in Derbyshire, England, were kept quite 
uninjured in moist peat, and pigs were found intact in a peaty 
soil near Dubuerton, Somersetshire. 
There is also a possibly protective action exercised at times 
by the organic acids themselves when they concentrate upon 
a nucleus of bony fragments, precipitates of iron oxide or amor- 
phous silica. This is done by their reduction of iron salts 
forming organic compounds, or by combination with silica in 
the dissolved silica of the infiltrating streams. The iron is 
liberated from solution by oxydation and the silica by decom- 
position, and both iron oxide and soft silica may be thus in- 
troduced into the interstices of the bone and serve as agents of 
induration. It is said by Von Haast that the moa bone layer 
at Glenmark is somewhat reddish. This may be attributed to 
ferruginous encrustations. Again, the action of organic acids 
on such material as the harder class of bone must be some- 
what limited by dilution, and the constant percolation of 
water from surface water-courses and rains must considerably 
neutralize the corrosive power of the readily dissolved vege- 
table fluids. Again, these vegetable fluids are quite liberally 
employed in making defensive combinations with the mineral 
matter brought to them in complete solution or mechanically 
