New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-06-21

t,.aa cha nn,or ,orn tho more complete crustaceah'
| and the still more highly organized inSco" ~" w
| paratve standing OF different classes III '"o ,oio
brate tne ia 40 well that1 need not rccau IL 10
| -, 80 go ,ote any one Of these classes separately,
,vo 80, ,ho radiation inst marked with each GLASS;
| Tina, IL fishes reptiles, hirds, and mammals may DE
suhdyided according TO details of structure py when
they stand relatively higher or lower This series OF
rank eteru upon relatfFeoomphcaton OF srnctue'
IL gnized ny all BIOLOGISTS and IT, az have shown,
not aimple SERIES but involves endless minor series,
based in the same way upon structural characters
GRApkTIoN OF RANK PARAIIELEp IN GROWTH
| In what have called series OF rank graduation 1
allude euly animals in the adult condition. taking as
a standard OF comparison the complication OF their
structure when full grown. But have something OF
the same hind tie series determined by growth that
s. by the changes which animals undergo from the time
when the whole macs Of substance nothing but an aecu-
mutation Of yok cells. presently combining to form the
germ layer nesting the yok and successfully passog
through phases which develop the outline OF new
being and finally lead to the formation OF perfect fui-
| grown, living annual There ia, as We have SEEM a
mode Of development each type which may be looked
uDon as a unit All Radates, all MousEs, all Arhcu-
ates all Vertebrates are developed each within It's own
type according given pattern Of growth, and up 10
certain point where class features, 0rdlnal features
| family features, make their appearance, they show
only typical charaetersthatis, what belongs to tnem
as members Of their type but not what characterzes
type within each such general series Of growth
are minor SERIES determining special characteristics
/ The Vertebrates have mode Of development pc
| culiar to themselves, and similar thdt'
! as we have SEEM IL is difficult to distinguish
! the human embryo from that Of any quadruped. But
within that general Vertebrate series OF growth we nave
minor aud special series; those upon wmch tne
dog the deer the guinea pig, and any gwen group OF
Verebrates developed SO IN the BIRDS their CROWN
as a whole reminds MS Of the quadruped stnkngy; pu'
they have their invarable aud unfairly speclhc noues
of growth determining their final character as belonging
| 10 some particular group OF birds In those animaS
whose embryoogy has been carefully studied the ln
yestjcator is not mlsed by general resembances' LOT
We can anticipate the final result by its connection Win
antecedent phases and in each case the sdlliW em
! bryOogst recognizes the pecuiarites which are 'ne
precursors of the ultimate complication OF structure
Looking upon all these of Vertebrate growth rs
whole in the same way that look upon the type OF
adult Yertebrates as whole, we see both sets OF
phenomena as single pictures all the minor series OF
rank and growth melting into one simple series WHICH
includes them all. Looking upon them boIh III this
comprehensive way can fairly comp are them IheTe
is a time when the human embryo is 50 like the hsh en-
bryo that hard 60 say what is specifically human
and what is specifically fish later it may be compared
TO the reptile aud to bird and its Characters
ties are supermposed upon those which 1t has In com
mon with the lower representations OF the type
Such a series Of growth, corresponding with
series OF rank graduation, We have among
Vertebrates among Ariculates among Molusks, and
among Radiaes. II you will carefully compare its diff
ferent phases OF development you VIII fnd that an in
sect during what call its metamorphOss represents,
first the lowest Articulaes the worm, IN It's cater
pillar condition then the crustacea in its chrysas
state and only takes its insect features wlen it IS
fuu grown
GENERAL FACTS As TO STRUCTURAL GRADATIoN.
In certain sense the structural history OF every lha
..--t..- may
said TO be the structural history the whole type It's
little more legIDe the common observer In the Ar
ticuates than in any other type, because the ghest
class undergOes fs growth the distinct chapters OF
connected metamorphOss but it Is equally true for all
II had time could show you in detail That the Ecn-
oderms instance. when forming in the egg, have
first, pOypike, then acaephllke features and that |
when they nay assume characteristics OF their class
supposng that they belong to the hs Ter species OF
Echn0derms). they pass through phases OF the lower
families before they attain their own specific features
In short, we may say that the classes within every
type the within every class, the families within
every order, the genera within every family and the
species within each genus, present structural grad-
ou more or less marked. The embryoogy OF the higher
animals each type helps us to understand TINS grla
ton by showing it TO Us in progressive development
do not mean say that any emDryolOgy corresponds
ia all its details 10 the structural relations OF
flll crown;anmals. But when fad That reptile |
is dsbllke before 1t assumes reptilian character
that birds and duadrupeds are fish and rcptnelke be-
fore they develop Their class features aud that even the
human embryo passes through phases resembling all !
these lower groups may be quite sure that the rank
in which we had arranged them before we knew their
embryoogy the one, since their mode OF de-
yelopment confirms it, The same kind Of correspond
ence prevails between embryologcal development and
geological succession That Is fish were thc fast Verte'
brates introduced upon earth. Tnen came the ffeat
reptiles then birds, and latest mammals, qu4drupeds
and man. We do not yet know how far tieSo c"rre-
spondences may be carried for are not familiar with
the eInbryoloHcal history OF great many animals
But solar as science has gone in this nd OF uyossl-
tiob No results are everywhere the sane. Jite Tor
instance the Echinoderms the earliest representatives.
- that class of Radates were the Crnoids l'tarshes
on stems Now the EchinOderms Of the present day
pass through distinct crnodal phase OF Development
ana may add that there among the pres snt il0
derms lower group the members or winch arc always
attached to Ohe Pentacrinus and similar general
80 that in this the Of geological succession
Of chronological development, and of structural rank
among the living agree remarkably. could give you
yarous instances OF the KIND; but al these facts
belong properly 20 my course on g,olJAcaI succession
and paleontOlogy next term ana snO i only confuse
your minds did attempt to present them hVw Only
hiring forward enough TO snow tn.s basis Tor
the ardent discussion going on among natural
ists during the last tea or twelve years as
to the real nature Of these relations. The
eyolutonists as have shawn you ia the extracts with
which opened this lecture the parleiism between
the series Of embryonic growth and geological success
SION as supporting their theory. But even were the
par,elism as complete they would have ne eyl
dence is vtated by the fact that 1t extends to series
of rank among living animals, and, as could show YOU
cleo IN a series of the same KIND controlling the geo
! graphical distribution OF animals.
But even we're the correspondence confined to the sue
cessye appearance animals In time and their success
siye phases Of growth does it common descent
Does 1t give us any rational explanation OF the means Dy