388 REVIEWS—GEOLOGICAL EVIDENCES. OF MAN’S ANTIQUITY. 
planted by the oak, and the oak by the beech, can be but. vaguely con- 
jectured ; but the minimum of time required for the formation of so 
much peat must, according to the estimate of Steenstrup and other 
good authorities, haye amounted to at least 4,000. years:; and there is 
nothing in the observed rate of the growth of peat opposed to the 
conclusion that the number of centuries may not have been four times , 
as great, even though the signs of man’s existence have not. yet been 
traced down to the lowest or amorphous stratum.” 
With regard to the Lamarckian or Darwinian hypothesis, of which 
a general sketch is given in the latter part of his book, and to the 
bearings of Man’s antiquity on this theory, the author expresses him- 
self in somewhat indefinite terms, but with a manifest bearing towards 
an acceptation of Darwin’s views. There is a good deal of book-ma- 
King, however, in this part of the volume; merely a general resumé 
of the subject being given, without the elaboration of any important 
facts or deductions of a novel character. Having already discussed 
the leading points connected with this theory, in a recent volume of 
the Journal,* we need not extend the present notice by any lengthened 
repetition of the argument. The theory essentially supposes this.: 
that our so-called species, in place of being original creations, are 
really derivative forms—developed from types of earlier existence by 
slow accumulative changes, brought about, in themselves, chiefly. by 
a gradual alteration of physical conditions in surrounding Nature— 
In other words—an organic form of. any kind, is supposed to. be sub- 
ject to indefinite variation: and thus, it is maintained, all existing 
species have sprung during a long series of ages from. a few original 
life-forms, or even from a single parent-organism. Startling as this 
view must at first appear, it has nevertheless some strong claims to 
consideration. The principal of these, confining ourselves to the ani- 
mal. world, are as follows :—First, the structural and functional homo- 
logies which obtain, not only amongst nearly related types, but even, 
to some extent, throughout the whole animal series. Secondly, the 
resemblance between the progressive phases of foetal development in 
higher forms, and the permanent condition of inferior - ‘types. And 
thirdly, the presence of rudimentary or imperfect organs in various 
species. These tacts, which are in perfect harmony with the develop- 
ment theory, constitute grave difficulties when we strive to explain 
them in connexion with the usually received or ‘special creation” 
* Vol. vy. pp. 867-387 
