32 PLANT DISEASE 



carbon, only hydrogen and oxygen in the 

 same relative proportion as in water, it can 

 only be derived by synthesis from the carbon 

 that is set free, and the water that is received 

 through the roots." 



"If," says Sachs (82), "starch is the first 

 and sole visible product of assimilation, it 

 follows directly that all other organic com- 

 pounds of the plant must originate by chemi- 

 cal metamorphosis from it. If, therefore, 

 later the plant manufactures other carbo- 

 hydrates, fats, and finally proteids, all of 

 which contain carbon, it can only employ 

 starch as the starting point. 



" The plant must construct the highly 

 complex proteid molecule out of the simplest 

 inorganic compounds, carbonic acid, water, 

 salts and oxygen, while the animal obtains, 

 already formed, the proteid food, without 

 which it cannot live." 



From the foregoing evidence it is clear the 

 carbon compounds of plants are obtained 

 from the carbon of the starch, and, as I have 

 previously pointed out, the carbon of the 

 plant, and therefore of the starch, is governed 



