94 MISCELLANEOUS PARTICULARS. 



out; when producing eggs, its appearance is unmistakable. 

 Both testis and ovary may further be recognized by a thread 

 leading to the end of the lower bowels — in one case the spertn- 

 duct, in the other the oviduct ; the latter is usually much the 

 more conspicuous, as it at times transmits the perfect egg. 

 There is no difficulty in reaching the site of these organs. Lay 

 the bird on the right side, its belly toward you : cut with the 

 scissors through the belly-walls diagonally from anus to the 

 root of the last rib — or further, snipping across a few of the 

 lower ribs, if these continue far down, as they do in a loon for 

 instance. Press the whole mass of intestines aside collectively, 

 and you at once see to the small of the back. There you ob- 

 serve the kidneys — large, lobular, dark reddish masses moulded 

 into the concavity of the sacrum (or back middle bone of the 

 pelvis) and on their surface, towards their fore end, lie testes 

 or ovary, as just described. The only precaution required is, 

 not to mistake for testicles a pair of small bodies capping the 

 kidneys. These are the adrenals or " supra-renal capsules " — 

 organs whose function is unknown, but with which at any rate 

 we have nothing to do in this connection. They occur in both 

 sexes, and if the testicles are not immediately seen, or the 

 ovary not at once recognized, they might easily be mistaken 

 for testicles. Observe that instead of lying in front, they 

 cap the kidneys ; that they are usually yellowish instead of 

 opaque whitish ; and that they have not the firm, smooth, reg- 

 ular sphericity of the testicles. The sex determined, use the 

 sign ^ or 9 to designate it, as already explained. In the very 

 rare cases of impotence or sterility among birds, of course no 

 organs will be observed ; but I should dislike to become respon- 

 sible for such labelling without very careful examination. The 

 organs of a small bird out of the breeding season are never 

 conspicuous, but may always be found on close scrutiny, unless 

 the parts are disintegrated by a shot. 



§47. Recognition of age is a matter of ornithological ex- 

 perience requiring in many or most cases great familiarity with 

 birds for its even approximate accomplishment. There are, 



