76 THE IMPOETANCE OF BIRD LIFE 



as soon as it is laid. The use of artificial light 

 has also been tried, the object being to prolong the 

 daylight hours. Although some flocks have 

 actually been made to increase their output by 

 this means, the practical value of the system has 

 not yet been wholly proved. 



Arriving at the consumption of eggs in the 

 United States, we find that it matches that of 

 poultry. There were more than a billion and a 

 half dozen placed on the market in 1919, or about 

 180 eggs per capita. New York City alone daily 

 consumes between three and four million. The 

 production in the United States, though it did 

 not reach the figures of the previous year, was 

 valued at more than half a billion dollars. The 

 average adult city dweller annually spends about 

 $20 on eggs. 



But, despite the enormous quantities eaten, 

 there is always a surplus left over. This is em- 

 ployed in a number of ways, for export, canning, 

 drying, and in divers industries. Although for the 

 present exporting is at a low ebb, there are en- 

 couraging signs that it soon will return to a pre- 

 war standard. The canning and drying of eggs, 

 however, continues, and each year hundreds of 

 millions are cared for in this way. Calico-print- 

 ing consumes approximately half a billion each 

 year; book-binding, glove-making, and other 

 leather industries take about half that amount. 

 And before the ratification of the Eighteenth 



