40 FOOD OF THE VEGETATING PLANT. CHAP. I. 



tended to support. Du Hamel reared in the above 

 manner plants of the Horse-chesnut and Almond 

 to some considerable size, and an Oak till it was 

 eight years old.* And though he informs us that 

 they died at last only from neglect of watering ; 

 yet it seems extremely doubtful whether they 

 would have continued to vegetate much longer 

 even if they had been watered ever so regularly: 

 for he admits in the first place that they made less 

 and less progress every year ; and in the second 

 place, that their roots were found to be in a very 

 bad state. 



Which are But if they had even continued to vegetate, still 

 dent to th e experiments were insufficient to decide the 



de f^ d t ethe point in question. Their insufficiency was first 

 pointed out by Bergman in 1773, who showed from 

 the experiments of Margraif, that in one pound of 

 rain water there is contained one grain of earth.-f- 

 Earth, therefore, must have been absorbed along 

 with the. water; so that even the boasted experi- 

 ment of Van Helmont, on which so much stress had 

 been laid, amounted to nothing. For the rain- 

 water employed in the experiment must have con- 

 tained in it as much earth as could have been well 

 expected to exist in the willow at the end of five 

 years. And if not, then it is easy to point out 

 an additional source of supply : for it has been 

 shown by Hales and others, that unglazed earthen 

 vessels when placed in the earth, will readily ab- 

 * Phys cles Arb. liv. v. chap. i. I Opusc. vol. v. p. 92. 



