New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1877-01-19

IN treating the subject TO which these Voiuihes |
arc devoted Mr. Wallace starts from the principle
which he a.lrms Is now conceded by naiurallstS'
that by some slow process of development or trans
mutation. all animals have been produced from |
those which preceded them. The old notion that !
every species was specially created rs ii nov exists
at a particular time and in particular spot, he |
maintains is abandoned rs opposed 10 many striking
facts and unsupported by any evidence But the |
modification OF animal forms took place very slowly
SO that the historical period of three or four |
Thousand years has hardly produced any perceptible
change in n single species. The changes IN the |
forms of animals appear 70 have accompanied tue
changes of physical geography, OF climate or OF
vegetation. But as the minor features of the earhs
surface together with the structure and habits OF
ali living things are everywhere slowly changing |
white the great features of the carth,--the CONT
ncnts and oceans, and loftiest mountain ranges
only change with extreme sowness and alter very
long intervals il is evident the present distribution
Of animals is the final product of all these revol-
tons in organic and inorganic nature. The greatest
differences in the productions Of any part OF tho
elube must DEPEND isolation by the most ciiectua
barriers.
The natural tendency of animals is to roam IN
every direction in quest of food But in doing this
they meet with many obstacles. Rocks ana noun
tains have TO be climbed rivers aud marshes 70 be
crossed deserts or forests 10 b. trayerScd. while
narrow straits or wider arms of the sea separate
Islands from the main land or continents from each
other We must consider the facilities OF different
classes of animals for overcoming these obstacles,
and what kinds OF barriers are most elcctuai ~
checking their progress. Many of the largest mann
inalS are able to roam over whole continents Inc
elephant for example, is equally at home on plains
and mountains. 1t climbs to the rocky summit Of
Adams Peak in Ceylon, which Is almost too steep for
man TO ascend. IL tIaVerses rivers and forces its
WAY through the denscSt junEcs with surprising
case The tiger. the rhinoccros, and the hon have
eqnn powers of dispersal Wherever there is land
anu food there are no limits to their range Other
animals are more limited in their migratons' lie
apes, lemurs, and many monkeys can never pass far
beyond the limits of the forest vegetation. The
same is trnc of TIL squirrels, the oposSus, the ar
bocal ca s. and the sloths. Deserts or open country
are equally essential to the existence Of Others.
The camel the horse, the zsbra, the giraffe could 40
more exist ia fores; country than the jcrhUa OF
prairie marluot. Other animals confined TO
inonntains, and could not extend their range into
lowlaus forests The goats and the sheep are the
most striking groups of this kind, which find their
subsistence on the highest mountains Of the globe.
The animals which thrive best IN dry and hly
REGIONS find an eI.otaal barrier broad level or
naYshy valley. Migration Is often checked b. the
din cYcc of vegetation and Of insect life. On the
plains of the Amazon many species of monkeys,
binds. and even insects are f1uud up to thc nVcr
banks on oac side. but 90 not to the other. la
tie lower pa.t of the RIO Negro two kinds Of
,loukcys are found on the north baak OF the river
bat never on the south Very few mammals can
swim oyer an, considerable extent Of sea- though
many can swim we'll for short distances The
i,euar travcIscs the widest streams in South
Gu!sica aid the bear and bison cross the Mississippi
Deer take boldly to the water and ran swim TO 4
CERTAIN distance Squirrels, rats, and JENNINGS i'll
bands Of thousands aud hundreds of thousands pass
over rivers. lakes and even arms of the sea, bui
th..y usually perish in the salt water.
The migration Of animals ,s probably confined to
birds a4d fishes Most of the birds shat spend their
Spring and Summer in the temperate parts of Eu-
Top. pass the Winter in North Africa and Western
.a. The Winter ylsitaut5, on the other hand, pass
tie Summer in the extreme North of Europe and
asia, many Of them breeding in Lapland. TIE
ri.htiIcal, presents tyWtal example of a migra-
Ion. bird Daring the Winter months i; inhabits
North Africa, Asia Minor and the Jordan Valley.
Ea!ly in April it passes into Europe, and spreads
ever France, Britain, Denmark AID the south of
Sweden wh;c il reaches by the beginning of May.
ltdoes not enter Brittany, the ChanaCl Islands, or
the western parts OF England, never visits Wales
except the extreme southern point, and rarely
tend. lnrthcr north than Yorkshire. l. spreads
over Central Europe, through Austria and Hungary
t. Southern Russia AMI the parts OF Siberia
and breeds ~ the Jordan Valley The Sea?asSag. is
very dangerous to many birds. QG1ils cross in in
,n"lise i9Cks and great numbers are drowned at
whenever tho weather is unfavortblc. Aquatic
birds follow the routes Of great rivers and lakes
and he shares Of the sea. Ono great body reaches
Central Europe by way of the Danube from the
shores If HE Black Sea, another asccnds the RAOne
Nali.y from the Gulf Of Lyons.
The distribution Of animals as affected by the con-
G'tionS If the cartlfS surface is the subject OF
snguiariy interesting chapter, showing the authors
rqaarkstlo i,owcr of minute observation, and equal
IL remarkable habit of reporting facts with pre-
cisien end accuracy. Two important features of tho
clrtiis surface, SAYS Mr. Wallace, t. be cons;d-
cred IA their bearing this point. First, the large
proportion of water to land as indicating the vast
extent Of ocean by which many Of the continents
and islands arr separated IRON one another. Second,
the yinanncss Of the mean hight OF the land con-
pared with the mean depth of the water. The mean
hight Of the land surface it is computed does not
exceed a thousand feet; while the ocean bed not
only desccads deeper than the tops Of the highest
morhtains rise above its surface, but these profound
depths are broad suuken plains, while the shadows
correspond Ia the mountain ranges that its mean
Ge7t as nearly can Dc asccr ancd is twelve thou
sand feet II is therefore highly probable that
AMONG the continual changes Of land and Sc the
amount of land surface has often been much less than
ii is now. Ii is moreover probable that large
masses Of land have been more isolated from the
Is than they al present, just South A'ncica.
would be if North America wcrc 10 SAX beneath The
ocean. o. as Australia wDud become il the Malay
Archipcago were submerged. We must also bear in
Iniad that the shallow paris Of the almost
always the vicinity Of land. and tlat degree OF