I'UiiKKTV. :•: 



wliich give birth to an incomplete being, tliere is observed an increase 

 in fecundity : the Bitch only yields two per cent, of its weight, but the 

 Calf absorbs twenty per cent, of its parent's weight. 



This unequal distribution of fecundity among the animal species is a 

 conservative element in the scheme of organic nature. The reproduc- 

 tivencss and the numerous chances of destruction surrounding the germs, 

 are compensated for in just proportion ; for out of many thousands 

 of ova furnished by the most prolific species, a comparatively limited 

 number only find all the conditions favourable for their development. 



CHAPTER I. 



Generation. 



The processes by which generation is accomplished are four ; these ai'e 

 <x>pulation, fecundation, (jcstation, and jnirturition ; but it is only on tlie 

 attainment of a certain age — that of pid^crty — that these sexual acts are 

 in activity, and they continue so for a variable period, according to the 

 species. During this time, ova from the ovaries, fecundated by the 

 male seminal fluid, are received into the uterus, and remain there for a. 

 regulated period, until they have become transformed into young crea- 

 tures possessing certain physical attributes and resemblances to their 

 parents. This is the gestation period, and is followed by that of 

 jiarturition, when the young are born. 



SECTION I.— PUBERTY. 



The generative organs of the domesticated female animals are, like 

 those of the human female, only in a state of greatest activity during 

 the prime of life ; and the most notable characteristic of their functions, 

 as in woman, is their periodicity. These functions lie dormant from 

 birth until puberty, when, somewhat suddenly, certain very marked 

 modifications occur throughout the whole organism, but particularly in 

 the generative organs of the male and female animals. In the first the 

 testicles become more voluminous, and in some species they leave the 

 abdominal cavity to be lodged in the scrotum ; they also begin to secrete 

 an abundance of a special fluid — the "spermatic" or "seminal," in 

 ^vhich particles of a definite shape — spermatozoa — and endowed with 

 motion, appear. This fiuid is stored up in the vesicnUe seminalcs, 

 which, until this period, were small and wasted-looking. The organ for 

 the conveyance of this spermatic fluid to the female becomes more 

 developed, and is capable of complete and frequent erection. In the 

 female the mammie enlarge, the ovaries are more vascular and turgid- 

 looking than before, and the Graafian vesicles are more or less developed. 

 The periodic ovipont then begins to be carried on, with all tlie 

 distinctive peculiarities that attend it, and which it is to bear during 

 the prolific period of life. 



The age at which animals arrive at pnhcrt]i or sexual maturity, is not 

 only dilTerent in different species, but is influenced to some extent by 

 the rapidity of their growth and the duration of their life. Domestica- 

 tion has more particularly brought about changes in this respect, and 

 by inducing a more rapid development of the organism, has hastened 

 the advent of this period. And it may be said that puberty is sooner 

 attained in the female than the male, and also that domesticity has 



