730 
Abortion in Cattle. 
mature birth. The period of viability, as compared with the time 
of gestation, vai'ies considerably in different animals, and can 
hardly be ascertained with positive accuracy ; but the follow- 
ing statements have been made in regard to this part of the 
subject : — 
Animal 
Period of gestation 
Viability at 
11-12 months 
10 months 
9-10 
7 „ 
Lamb and kid . . , , 
5 
4 
Pig 
3 
Puppy 
9 weeks 
7 weeks 
Kitten 
55 days 
45 days 
25 „ 
20 „ 
Abortion has attracted the attention of stock-owners and 
veterinary surgeons as far back as agricultural and veterinary 
records extend — unread and unregarded records, it would seein, 
but which may with advantage be put before the readers of the 
Journal in a concrete form. 
First, it is important to note that the subject of abortion is 
connected with the larger subject of embryology. Expulsion of 
a mature ovum occurs at every period of oestrum. This minute 
organ escapes from the ovaries into the Fallopian tubes, and 
through them into the cavity of the uterus. Not meeting, in its 
course, with the sperm-cell of the male, the dormant life is not 
aroused into action, and the useless egg is cast forth as a waste 
product along with the debris of the mucous membrane. Impreg- 
nation of the ovum checks its course, developmental changes at 
once begin, the embryo advances to the foetal state, and at a 
certain moment the uterus begins to contract, and the young 
animal is forced into the outer world. It is not known what 
changes suddenly occur to cause the expulsion of the foetus, nor 
why the period of parturition differs so widely in animals of 
different species or families. If the exact cause were known, 
it would perhaps be easy to solve the mystery of, premature 
expulsion of the germ. 
Investigations into the nature and causes of abortion, which 
have been carried on for the last century by veterinarians over a 
large portion of the civilised world, bring one fact out promi- 
nently — viz., that abortion is a product of civilisation. Wild 
races, so far as can be ascertained, enjoy an immunity from the 
disease in the epizootic form. As the result of common 
causes, i.e., violence, acute disease, exertion, excitement, or 
fear, abortion may be classed with other accidents to which 
animals are liable under all conditions of existence. 
