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VOI.. l.XXVI. 
XKW YORK, F1:P>1{T\\RY 1917. 
Xo. 4415. 
The Making of an Egg 
Marvelous Manufactory of the Hen 
ACE IXTREASE.—Tf a ])air of fowls jn’otluced 
10 fowls, five males and five feinale.s, in one 
year, and if these five pairs each produced likewise 
five i)airs the second .vear. and if this rate of mul¬ 
tiplication continued for 15 years, there would be 
produced fil.O.T).150.250 fowls. This rate of multi¬ 
plication is normal, and the result fjives some idea 
of the stupendous power of reitrodnction. which is 
a ]»rocess whereby new though similar individuals 
.are jrenerated from parent forms, thus ensuring the 
l»erpetualion of the species. 
EORIIIXC THE E(J(!.—In most of the higher 
forms of life, including the fowl, the mode of re¬ 
production is complex. The organism is coin,|»osed 
of many cells, varying in kind and .structure, one 
grou]t of cells forming one kind of tissue and an¬ 
other groui» of cells another kind of tissue. Each 
v.ariety of tissue is especially fitted for performing 
one function, such as reproduction by the repro¬ 
ductive tissue. This reproductive tissue exists in 
th(‘ form of definite oi’gans. and these give rise to 
the formation of germ cells, 'riiere are two kinds 
of germ cells forimal. (>gg cells in the female and 
s]ierm cells in tin* m.ah'. .Vinong fowls and other 
// 
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A Quarter of a Mile of Leghorn Pullets in a New York Cornfield Fig. 49. See Next Page. 
life developed oidy from pre-(>xlsting similar forms, 
RODY (’ELLS AXI) CEIt.Ai ('ELLS—Which came 
first, the hen or the eg.g? Donlitless the great ma¬ 
jority to whom this fpiestion is put will state that 
the hen came first, ar.iruing that the hen was neces¬ 
sary to i)roduce the e.gg. We shall see. The body 
of the fowl is composed of two kinds of cells, the 
body cells and the .germ cells, the egg is the germ 
cell while the hen herself compri.ses the body cells. 
It is quite natural to a.ssume that it is by nieans 
of the egg that the hen is en.ahled to reproduce her¬ 
self. This is the old conception of the relation 
between successive generation, which is that the 
f 
hen produced the e.gg in order that ii chick mi.ght 
be generated. The e.gg was considered the medium 
of development. Such is not the case, however, 
for we have ali-eady noted that before a chick can 
be generated there must he an egg; that is. the egg 
is responsible for the development of the chick. 
The e.gg came first. The answer to the question is 
well stated by Samuel lUitler: “It Js not to say 
that the hen produced another hen through the me¬ 
dium of an egg. hut to say that a hen is merely an 
e.gg’s way of ])roducin,g another e,gg." 
FOOD f'lT.VX’OES.—It is not intended, however, 
that this article should he a discussion of biological 
problems hut rather a discussion on the manner in 
a hen were killed while in a laying condition there 
would appear in the ovary a large number of 
oocytes of different size.s, looking much like a clus¬ 
ter of grape.s,. There appears to he a far larger 
nntnher of oocytes in the ovary than ever develop 
into eggs. In an examination of 15 hens Pearl 
found from 914 to .‘).d05 visible ooc.\tes i)resent. and 
with the aid of a microscope 19.475 were fouml in 
one ovar.v. Each ooc.vte is enclosed in a lining 
called a follicle and as the oocyte increases in size 
a white streak appears on one side of the follicle. 
This white streak is called the stigmata. On the 
comidetion of growth the ooc.vte becomes an ovum. 
When the ovum reaches the size of the yolk it es¬ 
capes from the ovary through the rui>tnr(> of the 
follicle along the stigmata. The purpose of the 
sti.gUKita. therefore, is to allow tiu' o\’uni to escape 
from the ovary to the oviduct. 
fillE E(tO-^LVI\ I XO PR()(’ESS.—I'he ovum (>C 
the fowl is comparativel.v large* and is round in 
shape: it becomes the yolk in a fully-formed eg.g. 
Although the ovum is so large it is a single cell, 
the yolk mass h(*in.g composed of a large niunher 
of spheres which s(>rve as nutrition for the emhr.vo. 
At the time the ovum eseai»es from the foilicle it 
it enclosed in a lining called the vitelline numi- 
hram* and ni»on escaping the ovum is grasiied l,g 
hi.gher forms of animal life one group of individ¬ 
uals form egg cells only and such individuals are 
called feinale.s, while another group form .si)enn 
cells only and these are called male.s. In order that 
reproduction may proceed, to give rise to new in¬ 
dividuals, there must he a union of an egg cell and 
a .sperm cell, and the product resulting from this 
union is a fertilized egg cell. The proce.ss involved 
in the union of the egg cell and the .sj)erm cell is 
known as fertilization. The fertilized egg cell .gives 
rise to a new individual and completes the cycle. 
LIKE REOETS ITKE.—It is generally under¬ 
stood that “like tends to beget like’’ in all forms 
of life. It is never expected that the egg of the 
turkey would develop into a go.sling or that the 
egg of the chicken would develop into anything 
other than a chicken. This conception of si)ecifie 
org.anization was not alwa.vs held, for Ai-istotle be¬ 
lieved that eels were .generated from mud and 
slime. The writer well remembers that Avhen a lad 
h(> u.sed to i)ull the hairs from a horse's tail and 
place them in water in the belief that they would 
generate into small snakes. The belief that living 
material mi.ght Ik' generated from non-living mate¬ 
rial gradually became restricted however, until 
through the demonstrations of Pa.stenr and Tyn¬ 
dall it was shown that even the lowest forms of 
which eggs tire jiroduced. The hen has been called 
a manufacturer hectuise she hikes the rtiw pro¬ 
ducts, grains and other foods, and makes them into 
the fini.shed product.s, flesh tind ogg.s. The foods 
are changed into new materials which are ah.sorhed 
into the body; .some of these new materials are used 
to carry on the various functions of the hod.v, some 
tire used to keep the body Avarni, some are used to 
build up the tissues and to keep them in repair and 
some are u.sed to nnike e.ggs. The orgiins of the 
fowl used in nniking eg.gs are the reproductive or¬ 
gans, the ovtiry jind the oviduct. 
ERG FOItlMATlOX.—The ovtiry functions in the 
formation of the e.gg cells jind these p:iss throu.gh 
the oviduct whore vtirious substiinces are secreted 
before the egg is laid. Althou.gh both ri.ght and left 
ovaries are formed in the embryo, the left ovai-j' 
alone functions in the adult since the ri.ght ovary 
degenerates and dies in the early life of the chick. 
The ovary is attached to the wall of the body- 
cavity and lies in front of the left kidney. The 
oviduct Is a lar.ge coiled tube, about two feet long, 
extending from the region of the ovary to the 
cloaca. Throughout its length the oviduct is at¬ 
tached to the wall of the hody-cavity. 
EGG CELLS.— In the ovary the egg cells first 
appear as vi'ry small bodies called ooc.vtes and if 
the funnel of the oviduct. During its passage down 
the oviduct it rotates in circles and is surrounded 
by layers of albumen secreted by the glands of the 
oviduct. While the egg is in the alhumen secretin.g 
portion of the oviduct a special layer of alhumen 
is secreted which adheres closel.v to the vitelline 
membrane of the e.gg and at each end of the egg it 
appears in a twisted form like a strand. These 
strands of albumen are the chalazae and they may 
be .seen in a fre.sli eg.g if broken out of the .shell. 
The ovum is forced down the oviduct throu.gh [ler- 
istaltic action and more albumen is .secreted. The 
further down the oviduct the e.gg passes the thin¬ 
ner the alhumen becomes until the albumen la.-1 
secreted is quite watery. As the eg.g passes throu.gh 
the isthmus of the oviduct two linin.gs are secreted 
which enclo.se the albumen :yid tin* yolk; these lin* 
ings are called the shell-membranes. Fi-om tlie 
isthmus the eg.g passes throu.gh the uterus where 
more •lUmmen, which jias.ses through the sliell- 
memhranes, is .secreted. There is also .secreted in 
the uterus the shell and thus completes the forma¬ 
tion of the eg.g. Fiion being completely formeti the 
e.gg leaves the oviduct and is lanl. The time re¬ 
quired for the passage of the e.gg through the ovi¬ 
duct is generally from 21 to 27 hours. 
Macdonald (’ollege, (Quebec. 
MOKI.KY A. .lULL. 
