IRotee on Iboueing mxb Ibvaiene. 



By W. Geo. CRESWiii.1., M.D. Durh., L.R.C.P., F.Z.S. 

 [Continued front page 56). 



IN the case of our birds these essentials are best 

 found in roomy and open outdoor aviaries. In 

 such dwellings sufficient exercise can be taken 

 to keep the circulation active, and to prevent 

 the deposition of inordinate fat, since the birds are 

 enabled to find other amusements and interests than 

 merely to crack seed and gorge it. Therefore they 

 only eat as much as they require, and they digest it 

 afterwards. The more wind that plays around their 

 abode the more oxygen they get; and the more open 

 the aviary, the more access there is for the sun's rays, 

 and the less creation of draughts. No fear need be 

 entertained of the evil effects of mere uncomplicated 

 cold, that is as cold: all birds and all other warm- 

 blooded animals who naturally live in the open have 

 an arrangement of minute muscles whereby at will 

 their feathers and fur can be instantly made into 

 either an indifferently good or else a very bad con- 

 ductor of heat. When the covering is pressed tightly 

 to the body there is but little air contained in it, and 

 it is then at its best as a heat conductor ; but when it 

 is elevated and loose, tlie greater amount of air, which 

 is as it were entangled in it and so rendered quiescent, 

 makes it less of a conductor and therefore a more 

 effective preserver of the natural heat of the body. 



