, 1877-11-24


differs from the North American huiF.o,
and tins again from the Mongolian Yak,
The llama Of America replaces the cam
el OF Europe, the puma replaces the
lion. Brazil has had in times long passed
representatives, If its existing sltohs
and urmadillos. Australia, which has
isothcrmal zones like those 0t other con
tineNis, has no apes or monkeys, no cats
or tigers, no wolves ur bears, hyenas,
horses, squirrels, rabbits no woodpcckcrS
or phcasants. Instead of them it has
the.kangoroo, wombat, onithorhynchys,
cockatoos, and loyics, nowhere else
found. Whilst the environment thus
influences the organism, the'OrgGnism,
rcucting, influences the environment,
The most striking instance of this per
haps will be found on comparing the
constitution OF the ntmosphere before
and since the c.rbonitrrous epoch. Pm,
or to that epoch, all the myriads ot tons
Of cualy substance, now enclosed IN the
strata Of the earth, existed rs Carbonc
acid in the air. BY the agency of the
sunlight, acting on the leaves ol the
luXuriuut vegetation OF those times, tins
noyious gas was gradually removed, and
replaced by an equivalent volume OF
oxygen. y hot-bondcd, quickly rcspir.
iug animal could not possibly exist in
IN atmosphere laden with cmbonic acid.
Anterior 10 the conl deposit, the fauna
was cold-boodcd, and slow respiring
The fnla thus changed the aerial cnvi
runmcnt and thrs, in its turn rctcting,
changed the fauna.
Let us now rapidly survey tho chang
es that have taken place in the earth's
organisms In the earliest or primor-
dial period, there existed OF plants, only
water organisms, tangled sea weeds,
Then on the following period, the pri-
mary, came the more perfect cryptogams.
such as ferns. Then followed, in tie
secondary, pine forests In the coal
period the phanerogamia developed OUT
OF the more perfect crYptogamia. Not
until the chalk formation did the higher
coroiiilora appear. IN the beginning OF
the tertiary, thS earth had sufficiently
cooled at the poles, climate zones were
periodical, and the land was covered
with lraycd forests. FlOwerless plants
had been succeeded by flowenug ones,
the latter first without distinct corola,
and then by those with one, and Of these,
first the lower aud then the higher.
Turning to the order of succession OF
animal lte--of the primordin, - the
forms arc.skIlless Then in the lollow-
ing, the primary, come fishes. first those
with the he,erocerca TAIL as in the en-
bryo of existing ones. In the seconda.
ry, reptiles, and ont of them birds, were
developed; the decreasing amount of
carbunic acid, and the increasing amount
of oxygen, permitting the change. Of
birds, the earliest had IL long lizard like
tail, composed of thin vertebr,e; to every
one of which was attached strong rub
ber.like feathers, in pairs. The same
formation OF the ailpart OF the vertebral
column still occurs transiently in the
embryos of other kinds The trahsi-
tion from the reptile to the bird is
manifested by some of the latter having
teeth set in one order in grooves, in
another in distinct sockets. Among
mammals. us among fishes, the imperfect
orders appeared first. About the mid.
die of the mesolithiu period, out of a
branch OF the cloacal animals, the mar
supials were evolved; and in the begin
ming ofthe tertiary the placcntals were
developed out Of the marsupials. The
latter were at one time distributed over
the whole earth; now they are fast ap-
proaching extinction, In Europe, Asia,
and Africa, not single member OF the
group remains. The cloacal animals,
the marsupials, the placeutals, therefore
stand in an order Of succession. Such
has been the order OF evolution in Eu.
rope. For lis order in America may
refer you TO the recent admirable ad-
dress Of Prof. Marsh before the Ameri.
can Association tor the Advancement Of
Science. The general conclusions at