38 OF THE ASSIMILATION OF CARBON. 



the results he obtains and the views proposed by 

 the other. 



It is too much forgotten by physiologists, that 

 their duty really is not to refute the experiments of 

 others, nor to show that they are erroneous, but to 

 discover truth, and that alone. It is startling, when 

 we reflect that all the time and energy of a multi- 

 tude of persons of genius, talent, and knowledge, 

 are expended in endeavours to demonstrate each 

 other's errors. 



The question whether carbonic acid is the food 

 of plants or not, has been made the subject of 

 experiments with perfect zeal and good faith ; the 

 results have been opposed to that view. But how 

 was the inquiry instituted ? 



The seeds of balsamines, beans, cresses, and 

 gourds, were sown in pure Carrara marble, and 

 sprinkled with water containing carbonic acid. 

 The seeds sprang, but the plants did not attain 

 to the development of the third small leaf. In 

 other cases, they allowed the water to penetrate 

 the marble from below, yet, in spite of this, they 

 died. It is worthy of observation, that they lived 

 longer with pure distilled water than with that 

 impregnated with carbonic acid ; but- still, in this 

 case also, they eventually perished. Other experi- 

 menters sowed seeds of plants in flowers of sulphur 

 and sulphate of baryta, and tried to nourish them 

 with carbonic acid, but without success. 



Such experiments have been considered as posi- 



