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authors themselves would recognise the mischief 

 bound to accrue from thus recklessly massing such a 

 population over so disproportionate an area. And 

 this disproportion is no less existent when we have 

 raised the height of the aviary from one foot to six or 

 even nine feet. There is exactly the same amount of 

 floor fouling in the one case as in the other, although 

 when the roof has been raised the overcrowding is 

 not so apparent to the eye. And as will have been 

 seen, it is the fouling of the floor which has to be 

 considered. 



The conditions of bird life in a cage and in an 

 aviary are in all respects different. A cage is always 

 in the dry. It is moreover kept in a human living 

 room, and for obvious reasons is therefore not allowed 

 to become obnoxious to the sensibilities of its owner. 

 Since its floor is of wood or metal and is easily 

 removable it is kept clean by daily scraping and 

 occasional scrubbing ; fresh sand (though generally of 

 the wrong sort) is daily supplied ; and the food and 

 water are usually outside the cage, and so through 

 that and the other conditions of cleanliness are 

 preserved from contamination with putrid and filthy 

 matter. It is this and only this which makes it 

 possible to keep a bird in health in the limited space 

 afforded by a cage. To put two hundred birds into 

 two hundred feet of aviary is another thing altogether, 

 as anyone who has ever seen an aviary may realize if 

 he will only consider the conditions necessarily 

 obtaining in these enclosures— where rain beats in 

 and fog stands thick, and excreta cannot dr}^ where 

 food and water are kept inside, and where the floor 

 cannot be perfectly cleansed except at lengthy 

 intervals. Indeed it is questionable whether it can 

 be perfectly cleansed at all. 



We therefore see how necessary it is to modify 

 the dictum of one bird to one foot if we are to give 



