CHAPTER VII. 



MISCELLANEOUS PAKTICULAES. 



§46. Deteemination 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 testicles; 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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