92 



And this natural heat is much greater in feathered 

 than even in furry animals. The great rapidity 

 of breathing, the enormous area over which the 

 inspired air is spread by the agency of the air sacs, 

 (for in spite of the paucity of bloodvessels in those 

 organs this counts for something), and the almost 

 continuous character of the ingestion of food in what 

 in our own case would be of exceedingly abnormal 

 relative proportion to the size of the body, all tend to 

 produce an amount of tissue oxidation and of meta- 

 bolism far in excess of that present in ourselves, 

 resulting as we see in a normal body temperature 

 which in a man would in most cases be an almost 

 certain harbinger of death. 



I hope that what I have said — although I have by 

 no means exhausted all that could be said on this 

 subject — will shew bird keepers what can be done 

 by them in the direction of housing their birds, not 

 only with impunity but even with advantage. I 

 advisedly say advantage, because there can be no 

 doubt but that with better general health there also 

 comes a greater number of fertile eggs, to be followed 

 in turn by more vigorous offspring. Before I took to 

 keeping my Canaries in the open the hens frequently 

 suffered from egg binding : now that they live under 

 more healthy and natural conditions they rarely do 

 so. This is easily understood when one remembers 

 that this trouble is practically never due to ana- 

 tomical abnormalities, (and very seldom to any other 

 mechanical obstruction), but that it is caused by 

 circumstances dependent on some phase or other of 

 bad health, or to say the least on want of hardiness 

 or on some induced want of power to resist such 

 influences as extreme cold. 



But in spite of all the advantages attaching to 

 outdoor aviaries, breeding in them with hen Canaries 

 is never quite an " exact science." Generations of 



