MILK. 
91 
The fallopian tubes are two tubes leading from the horns of the 
uterus to the ovaries. 
The ovaries or female testicles are small bodies surrounded by 
a firm, fibrous capsule. The substance consists of a network of 
tissue, blood vessels, etc., in which are embedded the ova which 
are destined, on being fertilised, to develop into the offspring. 
Impregnation. — The ovum on being discharged frOm the ovary 
is caught by the abdominal extremity of the fallopian tube from 
which it is passed on down to the uterus, where if it is unimpreg- 
nated it dies and is discharged; but if impregnated by the 
spermatozoa contained in the seminal fluid, undergoes certain changes 
which ultimately result in the reproduction of the species. The 
impregnated ovum goes through a series of divisions and subdivisions, 
until finally it becomes a mass of cells arranged in three more or less 
distinct layers which form the embryo. The embryo very soon 
becomes enclosed in membranous sacs developed from the middle 
and outer layers mentioned above and joining the foetal membranes. 
Connection with the uterus is obtained by little short finger-like 
processes (villi) growing from the outer surface of the external 
membrane (chorion) into folds or crypts in the uterine mucous 
membrane. The chorionic v-illi become surrounded by a plexus of 
maternal vessels thus bringing the maternal and foetal blood into 
close relationship. These structures are known as the placenta. 
Placentae are therefore those structures developed for the purification 
and nourishment of the foetal blood ; they are of two types :— 
(1) Deciduate, in which new maternal tissue is found in con- 
nection with the uterus during gestation and lost after 
birth, e.g.^ the human placenta. 
(2) Non-deciduate (animal) placentae. 
Placentae are also classified according to the disposition of the 
villi as — 
(1) Diffuse, when the whole surface is covered by villi. 
(2) Cotyledonary, when the villi are only met with in clumps 
or tufts. 
(3) Zonary, when the villi are arranged in a strap-like manner 
round the membranes. 
The placenta of the elephant is non-deciduate and zonary. 
Milk. 
The udder consists of two glands and is situated on the breast 
just behind the fore-legs. In the virgin state it is small, but during 
the latter period of gestation it becomes considerably enlarged and 
