642 STRUCTURE AND GROWTH OF DOMESTICATED ANIMALS. 
Concerning the anatomy of our domesticated animals there is a 
great deal known; enough to give a good idea of the peculiarities 
of the full-grown animals of the different kinds which we raise to 
use for various purposes. Concerning the functions of their organs, 
there is also a great deal known, which is of value and service to 
guide us in our treatment of them. Nobody expects to treat a 
pig as he treats a horse; and the difference in our management of 
two such animals is determined by what we know of their struc- 
ture, by what we know of the functions or the play of their char- 
acteristic organs; but there is one topic about which the farmer 
would like to know more, and that is in reference to breeding; 
and especially such’ points in the process of breéding as would 
enable him to do certain things which would add greatly to the 
value of our stock. If it were known how to raise male animals 
in places where it is desirable to have them in larger numbers, if 
it were known how to raise heifers in those regions where dairy 
farming is largely carried on, imagine what an advantage it would 
be to be able to determine beforehand the sex of the animals to 
be bred. Unfortunately, we do not know enough to-day to guide 
us in that direction, and yet I have not the remotest doubt that 
the time is coming when we shall be able to bring forth what we 
want, as we have been able to produce certain peculiar modifica- 
tions of the various kinds of domesticated animals to suit our pur- 
poses,— when we want beef rather than milk, when we want 
strength rather than delicacy of structure. Now, how shall we 
get at it? We have not the information. You may consult the 
men of science, the most learned men of the day in every part of 
the world, and they will say, ‘‘Upon these topics we have no 
satisfactory knowledge whatsoever.” It is to be reached only by 
studying the various functions connected with the process of 
breeding, by studying especially the earlier stages of the growth 
of animals with which we are familiar, and studying them with 
reference to that point. Upon that topic I will make a few state- 
ments concerning the facts with which I am familiar. 
It is not long since all animals were divided into two classes 
with reference to their breeding. Some were called oviparous— 
that is, egg-laying animals, which multiply by laying eggs, out of 
which a young animal is eventually evolved ; the others were called 
viviparous, —such as bring forth living young, after a more or less 
_ protracted gestation; and these two classes of animals were sup- 
