372 GENERAL ZOOLOGY 



bend the toes in perching are so arranged that the mere 

 weight of the bird keeps them contracted, so that even when 

 the pigeon is asleep the toes firmly grasp the perch. 



The Reproductive System. The spermaries (Fig. 191,49) 

 are oval bodies attached to the kidneys. The ovary of the 

 right side is not developed, but the left ovary is a large organ 

 situated near the kidneys. 



Development. Unlike most of our domestic animals, pigeons 

 choose their mates for life. After fertilization the ova or 

 " yolks " pass down the oviduct and are covered with secre- 

 tions from glands in different regions, first with the white, 

 or albumen, then with a thin membrane, and lastly with a 

 white, limy shell. The eggs are laid in a roughly made nest, 

 and are incubated by both parents in turn for about two 

 weeks, when they hatch. The young bird breaks through 

 the shell by means of a hard structure on the tip of its beak, 

 and makes its appearance covered with a fine down. It is 

 interesting to note in this connection that Darwin says that 

 some of the short-beaked tumbler pigeons, which have been 

 developed by artificial selection, have beaks so short that they 

 are unable to get out of the shell alone, and require therefore 

 to have the help of the pigeon-fanciers. For a few days after 

 hatching the young bird is fed by both parents with a milky 

 secretion afforded by the crop, and called " pigeon's milk." 



At first the young are deaf and the eyes are closed, but 

 both sight and hearing are acquired within a few days. 

 Professor T. Wesley Mills of McGill University, Montreal, has 

 found that in newly hatched pigeons the sensibility to touch 

 and pain is very noticeable, and that they are extremely sen- 

 sitive to heat and cold. The young birds rapidly acquire the 

 power to make coordinated or connected muscular movements, 

 and in a few days the voice develops. The independent life 

 of the pigeon, in some cases Professor Mills observed, began 

 about the thirty-fourth day after hatching. 



