276 AN EGG FAKM. 



hatching ovens use no thermometers but learn to distin- 

 guish different temperatures by the sense of feeling, and 

 attendants on incubators and brooders sometimes learn 

 to attain very great precision in judging tempera- 

 ture without a thermometer. The hen can do it with- 

 out a thermometer and without learning how. We wink 

 without learning how, because our ancestors did, and the 

 hen knows when eggs are warm enough to take their 

 turns in the outer ring, because her ancestors were liv- 

 ing thermometers. The movements of the hen to roll 

 her eggs give an increase of ventilation, and in very 

 warm, damp weather when she is not rolling eggs she 

 will occasionally bristle her feathers and open her wings 

 a little to give her nest a slight airing, and if very hot 

 and very damp will even stand upright a few seconds 

 by spells. Then, if it grows still hotter, she will leave 

 the nest entirely, sometimes remaining off for hours at 

 a time. If, on the contrary, it is windy, she will stick 

 closer than a brother, even when in need of food and 

 water. In very cold weather she is especially faithful to 

 her charge ; for she not only refrains from standing up 

 when rolling her eggs, but she does this while keeping 

 her body unusually quiet and holding her feathers close. 

 If the weather continues very cold she will remain on 

 her nest three days or more without food. The ten- 

 dency is for the eggs to assume positions in the nest 

 with the small ends toward the center, although with all 

 gallinaceous species of birds which sit on a dozen or fif- 

 teen or more eggs this order is not observed perfectly, as 

 it is in the case of such other species as lay only from 

 three to six. All eggs hatch best when the large end is 

 the highest. 



Nature being our instructor, we cannot excel her and 

 may consider ourselves fortunate if we come somewhere 

 near her. The most that can be claimed for artificial 

 hatching and rearing is, that while it can never operate 



