New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-04-05
THE GROWTH OF EGGS.

sTAGE-MARKED AND RAPID DIVERGENCE AFTER
WARD.
(PRoM AN OCCASIONAL CORRESPONDENT OF riiE TRBuNhl
CAMBRIDGE, Mass, April 1.-The following
lecture delivered by Prof AgassE, on the 2oth ut
before the Museum OF Comparative Zoology;
closed my last lecture with the remark that before APP
proachng the question of origin indispensable TO he
familiar with the conditions undcrw organized beings
we're multiplied 1t is feature which is too frequently
neglected. In any of this kind Ipropose to bring
before yeu as plainly and methodically can the
conditions accompanying the maintenance OF animal life
upon the earth do you realize that ali the living beings
which surround us. however great their diversity, have
a short time since been eggs; that there is not human
being nor a Quadruped nor bird nor reptile, nor
fish winch not been ovarian egg; that genera
ton after generation these eggs bring ferth new
beings like those from which they were produced ana
that this ia an indispensable condition for the very
istence Of all the life with which familiari But
this lie not all Besides the individuals capable OF pro
ducing eggs, there must DO corresponding set OF in'
divduas from whom the egg receives an impulse lead
ing 70 the formation OF the being within IT. In 0tner
words the egg must be started by an influence from
without that is by contact with sperm cells into those
successive changes OF transformations by which the
rev being Is produced. This is true OF all beings not
provided with the power Of reproduction by budding OF
Subdivision although. said IN my last lecture there
occasional exceptions 20 the rae, as among oeeS anu
certain moths and butterflies known TO produce living
beings by means Of nonecundated eggs We have many
animals among the lower organisms and especially IN
the class Of radates that combine the three modes OF
reproductions; multiply by eggs buds and Subdivision
at various times Others propagate by the two hrst
processes alone without the last Among the higher ami
mails propagation by eggs is the only method known
Neither mammal bird, reptile nor fish multpes its kind
in any way and among the artculates only some
OF the worms are known to propagate by selfdv!son
he kinds,
and BryozOa. maintain their kind by budding; and
among the Rsdiates, none of the higher groups,
neither the Hoiuthurans, star-fshes nor seaurchins
propagate by these methods. We find them
first in crnods though rarely, and II is only
lower down i'll the class, among acalephs and pOyps,
that they frequent. How these processes, and
especially that of budding compare with the ordinary
mode OF multiplication by eggs, shall have an oppor-
tuny Of discussing later. For the present limit my self
10 the process OF reproduction BY eggs.
THE FORMATION EGGs.
will now state as far as it l. known, what egg is
and how Is formed. As the egg grows steadily until
IL has completed its Transformation. It is difficult 10 give
description Of which Will for al these stages
since at every successive stage, while growing the egg
differs from what it was before and from what it is TO be-
All eggs however. arise In what called ovaries.
These clusters of cells, forming punches Of some
what gsnduar character in appearance Between these
cells the formed and in such way as at first 10
he hardly distinguished from the cells themselves. The
same sperm cells. which arise in Of the
Same character the Ovary and formed in man
ner perfectly similar that of the formation of the egg
50 we have these two spheres Of growth which charac
ierize in the animal kin dOm. arising III conditions
so very similar that the Of the two is hardly TO
be- determined by observation. 1t is only by the process
Of growth by the influences produced by the one upon
the other by the consequences Of these influences
that We recognize essential difference which dstin-
cuisines them.
IN order fully to appreciate what eggs are, we must
remenber-what has been known Tor about a half cen
tury onlythat all organized bodies are composed Of
little bags which are called cells and which formed
aud multiplied in various ways Most Of these cells are
small that they only be perceived by the aid Of
high maEufying powers. There are, 1t is true few
cell structures large enough be with the naked
eye for instance the cells Of common elder pith,
the cells Of the IL is Of the great
problems OF modern research TO ascertain how these
oes formed and what is their mode Of reproduction
For it does not that cells formed III the same
way under all circumstances. Some naturasts assume
that thc animal substance secreted by living body,
such "a milk which is secreted by the mammary glands
OF similar substances secreted by other organs certain
PARTICLES become eenters Of action around which other
particles crowd and when little collection Of this kind.
mcrOscopically small, has been formed an envelope
arises around H. aud have the utroe OF CELL Others
believe that minute imperceptibe particles Of animal
tsle bag formed cell envelope in short, which nils
as II enlargcs into hnd substance.
DIFFERENT VIEWS ABOUT OBSCURE PROCESSES
There those also, who assume that the two modes
OF cell formation exist simultaneously in the same being
1t is necessary for my purpose that should here
enter into critical discussion of this subject Unques
tOnpby new cells co arise within other cells from the
clustering together OF PARTICLES and utrces are formed
by the aggregation Of minute atoms Of animal substance
The process is very difficult TO follow and in watching
ia reminded Of what astronomers tell us OF distant
bodies in space which, when observed with the highest
magnfyng power appear ionly like irregular clouds OF
dust while others circumscribed in definite areas,
and seem more like celestial bodies with which
we are familiar We DEAL it were, with the nebular
world OF animal structures. The mysteries OF cell
formation are indeed as difficult to trace the
neBu8 Of the astronomer. We should not won
der then. If philosophers and observers are not oil
agreed upon the Interpretation Of phenomena. which
not only difficult for the mind TO apprehend but which
the eye finds it difficult TO discern. Investigators
not always agreed upon the facts themselves far less
upon their interpretation 1t part of true culture TO
refrain from Judgment and from expression OF opinion
where observation fails u.s. What we seek may. per-
hsps only be ascertaned when better observers and
better appliances for observation secured. Differ
OF opinion grow also out OF the different power
and prepare the investigators. Two bring TO
the same problem abilities and training which influence
their results powerfully They may honestly come TO
very different conclusions only the positive demon
sraon Of facts through improved means OF observation
will settle the question.
OVARIAN EGGS AND ELEMENTARY CELLS THE SAME.
As yet we know but imperfectly what cells are; stl
more inperfectly do know how they are formed,
and still less do understand their function. Yet the
amount OF facts already ascerained respecting them
truly overwhelming. This much, however, may be
postiyely stated between ovarian eggs in their ear
est condition and cells in their elementary state. such as
constitute the substance Of all animal bodies there is no
essential difference may be truly said that the egg
only a cell of peculiar Knd produced under particular
conditions in the animal body for specific object But