HEREDITARY DEFECTS OF DOMESTIC ANIMALS. 
355 
that harmony be preserved, and that no variation be induced in¬ 
compatible with the proper performance of all essential functions. 
Domestication is specialization. 'The wild animal is a o'eneral- 
purpose animal. When we destroy by specialization the essen¬ 
tial harmony of the animal body, we induce a defect which may 
vary in character, but may be largely included under two heads : 
i. Ariested development of a part ; 2. Over-development of a 
part. . Should one of these defects be present in an exalted de¬ 
gree, it is generally classed as a monstrosity, and usually tends 
either to compromise the life of the monster or prevent it from 
procreating its kind. 
Among the various hereditary defects, arrest in the develop¬ 
ment of a pait is probably the most common 5 and since in do¬ 
mestication the safety of the young animal from enemies and 
starvation is guaranteed to a high degree, the reproductive func¬ 
tions are in a measure repressed to avoid overproduction, a re¬ 
pression which is carried so far that arrested development of the 
reproductive organs is common and important. Notable amono- 
these is the arrested development of the testicles of the male. * 
Early in embryonic life the testicles are formed just behind 
the kidneys, from which position they usually descend shortly 
prior to birth, pass outside the abdomen and rest in the scrotum. 
Arrest this process and a cryptorcliid orridgling is produced, the 
testicles remaining within the belly. -■As we castrate more than 
99 per cent, of male animals, and since these “ridglings” re¬ 
quire the services of a specially skilled operator at a price several 
times as great as that required for the ordinary male, the defect 
assumes considerable economic importance. Tn the horse the 
hidden testicle renders the animal disagreeable, unsafe and 
vicious ; in meat-producing animals the meat is unfit for food. 
The hidden testicle is impotent, so that while an animal with 
one hidden testicle and one normal testicle breeds readily, one 
with both testicles hidden is sterile and ceases to perpetuate his 
defect. Few defects are more strongly hereditary than the hid¬ 
den testicle ; it is transmitted with great fidelity by the male 
naving one normal and one hidden testicle, and we have no 
doubt is also transmitted in a less degree by females begotten by 
defective sires. ” ' 
. There was recently presented at the New York State Veter¬ 
inary College clinics for other reasons a lamb having one hidden 
testicle. Inquiry revealed that the owner had bought in 1897 a 
fiock of ewes all apparently sound, and one ram supposed to be 
normal. In the spring of 1898 the ewes gave birth to a total of 
