908 The American Naturalist. [November, 
matter in fermentable masses, have come to be regarded as 
most universal and persistent in their influence. It has been 
shown by Dr. H. C. Bolton that organic acids may be success- 
fully employed for the detection and separation of mineral 
species, and Dr. A. A. Julien (Proc. A. A. A. Sci., 1879) has 
gathered together in a comprehensive review such inferences 
of their geological action as observation of their influence to- 
day permits. These acids’ dissolve iron salts and effect disin- 
tegrating effects upon hydrated or soluble quartzes. Such ac- 
tive and omnipresent agencies must exert a very appreciable 
influence upon animal remains, and in conjunction with car- 
bonated waters must render their preservation precarious. 
Terrestrial vertebrates, whose remains in the soil of forests or 
grassy plains would be exposed to the injurious attacks of 
these vegetable extracts and products, would run some consid- 
erable risk of being destroyed.” The placement of such fossils 
must be somewhat modified for their effectual integrity. It is 
true that swamps in whose periods of existence many succes- 
sions of spagnum layers with the associated accumulation of 
related and contemporary plants have stored up great quanti- 
ties of organic debris, have been the repositories of bones, and 
the great vertebrates, whose bones have become inhumed in 
their acid-laden depths, have been extracted in a reasonable 
state of preservation. But it is also true that these heavy 
bones have worked their way down through the superficial 
and organic layers to clay marl and sandy bottoms, where 
they were largely protected from the corrosive action of the 
humus acids which infiltration and drainage of surface waters 
would have partially removed. 
ë The vegetable or organic acids are mainly humic, crenic, apocrenic, with 
which there is an adventitious mixture of oxalic, malic, acetic and fumaric acids, 
which, according to Julien, are introduced “at least temporarily by the leaves, 
stems, etc., of most plants, many of which are rich in raphides made up of minute 
crystals of these acids or their salts.” 
7It is a matter of common | ledge that the t f goat 1l d by boas 
undergo solution in the animal acids of their host, so that tthe calcareous exuviae 
scarcely equals a tenth part of the original mass of bones, while the so called 
album graecum in the faecas of dogs, hyaenas, etc., represents the residue of di- 
gested bones. 
