CHAPTER VII. 
MISCELLANEOUS PARTICULARS. 
§46. DETERMINATION OF SEX. This is an important matter, 
which must never be neglected. For although many birds 
show unequivocal sexual distinctions of size, shape and color, 
like those of the barnyard cock and hen for instance, yet the 
outward characteristics are more frequently obscure, if not 
altogether inappreciable on examination of the skin alone. 
Young birds, moreover, are usually indistinguishable as to sex, 
although the adults of the same species may be easily recog. 
nized. The rule results, that the sexual organs should be ex- 
amined, as the only infallible indices. The essential organs of 
masculinity are the festicles; similarly, the ovaries contain the 
essence of the female nature. However similar the accessory 
sexual structures may be, the testicles and ovaries are always 
distinct. The male organs of birds never leave the cavity of 
the belly to fill an external bag of skin (scrotum) as they do 
among mammalia, they remain within the abdomen, and lie in 
the same position as the ovaries of the female. Both these 
organs are situated in the belly opposite what corresponds to 
the ‘small of the back,” bound closely to the spine, resting on 
the front of the kidneys near their fore end. ‘The testicles are 
a pair of subspherical or rather ellipsoidal bodies, usually of 
the same size, shape and color; and are commonly of a dull 
opaque whitish tint. They always lie close together. A re- 
markable fact connected with them is, that they are not always 
of the same size in the same bird, being subject to periodical 
enlargement during the breeding season, and corresponding 
atrophy at other seasons. Thus the testicles of a house spar- 
row, no bigger than a pin’s head in winter, swell to the size of 
peas in April. The ovary (for although this organ is paired 
originally, only one is usually functionally developed in birds) 
will be recognized as a flattish mass of irregular contour, and 
usually whitish color; when inactive, it simply appears of finely 
granular structure which may require a hand lens to be made 
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