New-York daily tribune., 1856-08-28
.s,pJoIN ASSOCIATION soR TIE I'D
. "i ~ IYANCEMENT or SCIENCE.
,rsSIoN OF 1886.

II nsyeoprnn, He .ad ! attempted yesertsy
70 show tbst, having once ascer alned TOE coz
that exists bet veen the eggs OF al an.mss, hENns
scx nd that they have a comnIoO genera stfat,uie,
hayinp shosn that their structure 1encs to ths
..Ipe,gral features Of the body OF fuLgroFn snin1s
and 70 the elementary tissues OF the oo1y OF iu.
xrown animals and plans, se bave oS'hen oa7-
which hss been already a. our hand for eeverd years.
II vas then time 10 make another step, 1G1 t1st sep
vss 10 know bow these eegs originate, ana whetheT
their similarity, there were any ma
teral differences between them. Today propose "
sbo. bow the egg passes into the cOnoon {" en en'-
lxo into the condition of germ INTO the beginning OF
tie new individual being In ordsI 20 9ppaeIa
perhaps, the course am taking, and 70 make p ~,
We nust consider that we are gong IN rev rse o"ei
from vha has been done in other bran nee OF nauId
hs,orv voulo alu dc to wnat mas taken place in
animals living. Fishes, reptiles, birds mdu1'Ha
have been known, studied, compared WIN one
another and sl, their difference brought ou, pr ,nh
penty long before 1t was underst,Od that tney nad
characters in common to such extenf, mat oe-
tween their organizations, IN all theii Pai 1no.
vas absolute identity, that H., s..ic1 no,"I,Os9 ~
throughout. This broad generahIation N'ia 'In IN
the second step in the inyestls"ioh' i9 tue
strdv az The egg II has been just the reverse Embry
oloei ists studying tbs egg, have recognized
the uniformity of the egg throughout tne an,lnd'
kpcdom before they have been able 10 GIsIisu'eI @
The eggs of different classes OF amin ,s Ihat ths
sbouId have been naturally the case is plan ON TINS
fsct that the egg being microscope oO)sct requioS
high naepfyDg power, only i's geDerai features nave
been first distinguished, that 49, tnoe ieures ~nica
are CON mon to all. AS we low proceed more and
mo,e minutey in the microscopic analyls OF the de.
tails of the St uctue OF the egg, we begin 10 discover
differences between the details OF the egg oil dlnerent
clsesee have alre ady carried the investigation
far eIough to be able to ttate that there are st ho
uOlogies which will uI tie the eggs OF all veebr4tes
spilsr to the structural homologis which unite the
four cse es of vertebrates into one great type AT
this nomeIt will undertake to distiDgus an ovarian
sgx of an artculae from the ovarian egg OF an mol
hsc, if IL s placed on the microscope without my see
ing il before. The type structure OF the molusca der
fom the type of the arculates, ard sso from tua of
the rsdiates and vertebrates. Having common
character these eggs correspond TO the conditions OF
structure which MAINTAIN lie IN grown animals and
We have further notifications or rather typs Of this
character which characterize the great structural
types of the animal kingdom. And when we proceed
10 examine the character Of the cells wGich are deVe
oped in the egg of different cisses, we can 20 further
and designate class differences, and here ana there
family fiererces, though must confess the faml
differences which l have observed have not
been very extensive. Yet | have seen enough
70 say that there fair prospect of our being able IN
due time to classify different animals even by the pc
culisrtes of structure of their primitive egg. Now
that primitive egg, as have said, may grow to any
size different individuals Of the different classes and
families And there only structural dlilcrenCes bat
rot essential between the microscopic egg Of the chick
and the large egg Of the parent hen. The membranss
e IDENTICAL the differences in the conteIta and tler
structure are differences which have been brought
about by the successive growth of those mtcrmed ste
structures which are observed Quug tueSo 81 cesVe
stsges of the egg. When we see our hens lay eggs
the frrt year they are themselves born, we are at
led TO the conclusion that eggs formed very
rapidly. So it is with hens bat not with turtles. Eggs
of our turtles laid this Spring, and Olt OF which the
young turtles will be batched during this month, or in
Sep.embe,, have taken years to grow 10
that state 1t takes years for the ovarian egg
OF the turtle to grow TO the condition when 1t is ready
u be laid. We have, there fore in that egg history
pf years to investigate, changes to investigate
which are as important as the changes which lake
place in any animal which, after years, hss not
yet completed its growth. The changes, for instance
which take place in the growth of child up to the
period Of seven years from its BIRTH not more
tensive nor structuray more important than the
change which take place in the egg OF the turtle.
There opens therefore branch of inquiry. Phys
ology as scierce has dealt chiefly with the germ
something engrated upon the egg. i AIN nov goil &
TO show that this is not true. the egg is The apmsl
sef; the embryo is never separate aad distinct from
tke egg. 1t is much the egg the butterfly the
ceterp pillar. The caterpillar is only the young butter
Hy-the butterfly which has not yet developed its
wigs. These changes are brought about 10y Ill
6csons of structure which are continuous IN the same
being. The germ is nothing new in the egg; is only
the esq itself assuming a new condition; it s only
the esg itself growing into new fOrms il is the egg
itse the consttutve parts of which present greater
difference between themselves than they d. at en-
earlier period. That Il Is should be fully uudersoo',
must refer TO some investigations made upon the
egg of the Zen and upon the egg Of the turtle. Bat
psrbepe may be more easily traced in the hen, aud
70 viii present the fact with reference to the inter
nal structure Of the egg in the hen. The yolk OF a
ttns egg, when foil grown, presents an internal mass
which Is entirely composed of large oil globues, and
there oil globuts come up III sort of channel TO near
the surface Prof. Agassz figured globe with u
bottle in it, the bottle representing the internal mas of
oeagnous cells and the globe the entire yok. This
internal mass has been caled a cavity; but it is
not q cavity; it is not more limited Isepara ed
from the substance of the yolk than the stons
Of the Young peach is distinguished from the hesh
when they are but one uniform green mass.
Gut across tse young peach and you see that they are
one mass. Now here we have not an internal cavity
but portion of the egg more oily and the outer por
ton in which the albumnous cells are more numerous
On the lower side of the egg always keeping the
a the bottle up theee abu luminous cells larger and
On the upper sde smaller. They not to serve q.
food for the embryo; they are an organic structure
There in much structure here as there s in any eel
tuIar pant II has only no. an Intestinal canal It has
only not heart and bOodvessels. Ii is a cellular
structure such as we find for instance in the fun y in
che champignon, which nothing but cells Of different
form containing different elements in different parts of
their beoy. So is the egg composed of differen. ee
ments Of different quality and character Professor
AgasEs figured cells around the bottle in the globe,
drawing them quite large in the lower psr around the
base Of the bottle, and much smaller III tie upper por
on they were also larger near the outside than near
the oottle Now here toward the surface and toward
tie base that the cells not only smaller but
Of peculiar character. The interior is more oleagi
nour; the exterior is more altumnous. II is this ~
tsna unequal arrangement ut which caases tie yok OF
the hens egg suspenC ed az it is within the alba Den
remain IN exactly the same identical condition Whst
be the position given to the egg, the yok will
main with that part uppeimost pointing TO the Of
the bottel. have often been asked how knew in
opening the egg which side the germ was.
1t was no great merit in one - khOr.
IL is only natural that the organs which are
to form the orgsus of the chick should DE
uppermost nearest to the setting hen. Prof Axa'sls
nvened plate in the upper poriOo of his sgobe rest
ing IL the Of the Bottle, which he said repre-
sent4d the condition of he egg after slight ubation
II must be obvious then that the egg passed bodily
condition where region of lie surfsce appears
mark ed than the other, more limited than 1t was
before, and then is called embryo or germ. Now lot
how that embryo increases in size and IN sub
sance 20 whether there anything to suos'antidte
tba - fha nod n