New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-04-26
CHANGES IN THE EGG.
FIFTH LECTURE or PROF AGAssIz.

FIFTH LECTURE OF PROF. AGASSIZ.
EXTENSIVE ALTERATIONS IN THE zoo BEFORE fhh-
TIIIzATIoN- DwFIcULTHs PRESENTED TO TIN
EMBRYOIOGIsT ny THE FACTS oF iSHENfED
CIIARAOTgRIsTICs--RxT R.ORDrNARY RESULT of
SURGICAL EXPERIMENTS ny DIR. BROWN
sEQUARD.
IFRoa AN OCCASIONAL conRBsPosDEsroF rnE TRBUSE'l
CAMBRIDGE Mass, April 1S.-The following
lecture was delivered ut the Museum OF Comparative
Zoology April 10: ~.
have no intention OF presenting TO you
all the facts now known concerning reproduction
among animals, nor an analysis OF the whole SUD
iect but wish n possible. to give such picture
Of our present knowledge as will enable you 70
form independent opinions concerning enrrent theories
IL Is very difficult TO mako statements That shaii DE
correctly understood by those who not familiar with
the faets have thought therefore, II might be useful
for YOU 10 see In what way the Investigations are made
the results OF which have thus far laid before you;
with what precauon and inuteness the simplest FACTS
have TO be ascertained
DIFFICULTY OF OBTAINING ILLUSTRATIVE SPECIMENS
In order 10 give you such idea from tho animal
most easily DO had at all have selected the
hem brought here several eggs so prepared as
to show some Of the appearances described in my pey
Gus lectures Even tho first step In such an nyestisa
ton that Of obtaining tho necessary specimens Is not
without It's difficulty You would think nothing could DO
easier than obtain both hens and eggs from the nearest
market Not 80 You may open dozens OF eggs Droughs
for sale from the country, and find that not one Is IN
perfectly natural condition because the careless trans
portaton has changed the relation Of parts have told
YOU on former OCCASION that the white speck marking
the spot where the germ begins its development (what
naturasts call the blastoderm would always DO FOUND
floating on the top OF the yolk being kept In that posi-
ton by the strings OF albumen by which the yelk
suspended, as II were, In the egg. opened number
this morning without finding what wished to show you,
all the eggs had for examination having been Jerked
in market carts and exhibiting torn chaaze he string
OF albumen by which the yelk is held in poston and
only succeeded by borrowing eggs from neghbor VINO
keeps hens 1 pass you one In when
you see the little speck floating on the
surface OF the yelk, the beginning OF the
germ Here Is another egg prepared In the same way
and showing the thing, though in this specimen
one OF the strings broken 1t Is not so easy to prepare
an egg for Investigation as you may suppose There
Prof Agassz showed how to open egg from the side
so "a TO cut the she'll lontudnaly Various specimens
OF open eggs passed around In enc OF these two
eggs you can see the membrane which lines the she'll
ana covers the white In the other the membrane Is re-
moved together with part OF the white, in order that
you may see how the white is deposited In layers Here
are two hardbOiled eggs cut longtulinay, so as 10
show the position OF the yek exactly In the center OIL
one while IN the other 1t side. The first has felt
no influence from the hen in the second the yelk mas
been drawn on one side by the warmth OF the hen as she
brooded upon 1t. You also In these eggs the ar
chamber at the blunt end OF the egg, and you VIII oD
serve that these air chambers are lined by TWO meln
branes which are be distinct at that end OF the
egg hut which unite to surround the white
EARLY STAGE OF OVARIAN EGGS OF HEN NArURAL slZEl