CHAPTER II. 



THE PLAxNT AND ITS FOOD. 



The food of plants " Vital foi-ce " Ot/ier errors Liebig 

 and Boussingatdt The botany of agriculture. The 

 synthesis of carbohydrates The physiology of plant- 

 nutrition. The persistence of misconceptions. 



The year i860 may be regarded as a landmark 

 of importance in the history of plant physiology, 

 for it was in that year that Sachs discovered that 

 the bringing together of water and carbon-dioxide, 

 in the green chlorophyll-corpuscles of the plant 

 exposed to sunlight, results in the formation of 

 the grains of starch found in these corpuscles. 



Previous to this date Dutrochet (1826-37) had 

 introduced the then crude idea of osmosis into 

 physiology; vegetable anatomy had improved, and 

 the modern conceptions of the living cell, proto- 

 plasm, nucleus, etc., were slowly looming ; sieve- 

 tubes had been discovered, and the proteids and 

 starch in various parts of the plant examined ; 

 and the suggestion was abroad, replacing Liebig's 



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