AGRICULTURE, HORTICULTURE, ETC. 27 



On this topic he wrote with full knowledge, having 

 reared silkworms for thirty-five years. The King-, 

 Henri Quatre, shared his hopes, and gave him practical 

 encouragement. It is well known that a great industry 

 was thus started ; by 1780 the annual yield of silk- 

 cocoons in France was valued at near a million sterling, 

 while in 1848 it had risen to four millions. De Serres 

 sought to promote the cultivation of the mulberry tree, 

 not only because its leaves are the food of the silkworm, 

 but because he believed that the fibres of the bast would 

 be serviceable in the manufacture of cordage and cloth. 

 He also tried to revive the ancient practice of hatching 

 eggs by artificial heat. We learn from him that the 

 turkey, recently introduced from Mexico, had already 

 become an important addition to the poultry-yard, while 

 maize from Mexico and beetroot from the Mediter- 

 ranean coasts were profitable crops. Among the new 

 appliances De Serres mentions artificial meadows, 

 wind and water-mills, cisterns not hewn from stone, 

 and greenhouses. 



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