SCHULTZENSTEIN — NUTRITIVE CONSTITUENTS OF WATER. 125 



Russia. Curiously enough the majority have not given up the 

 theory of the nourishment of plants by carbonic acid and carbonate 

 of ammonia, and especially that of their nutriment by means of 

 the air, though Liebig's manure has proved a failure. 



The theoretic grounds which have been brought forward since 

 the time of Yan Helmont, De Greer, and Bonnet against nutri- 

 ment from the soil, and in favour of the sustenance of plants from 

 the air, have been constantly repeated, to the prejudice of science 

 and practical cultivation, without any thorough refutation. They 

 deserve therefore to be recapitulated and illustrated. Van Helmont, 

 in 1654, instituted an experiment of planting a willow, of 5 lbs. 

 weight, in a pot filled with 200 lbs. of dried earth, and watered 

 this in a covered pot with river- water only. At the expiration of 

 five years, the willow weighed 169 lbs. 3 ozs., and the soil after 

 being dried 198 lbs. ; so that the earth had lost 2 lbs., while the 

 tree, without reckoning the fallen leaves, had gained 164 lbs. On 

 this it was concluded that nutrition takes place by the decom- 

 position of water and from the air, without a knowledge of the 

 large quantity of humus contained in the river-water, which was 

 more than enough to supply the whole of the increase. Similar 

 experiments were made by Eller (1752) and Duhamel (1748), and 

 admit of the same explanation, the error involved in them being 

 inevitable so long as the quantity of humus in spring- and river- 

 water was imperfectly known. Bonnet sowed in a wet sponge 

 and moss oats and barley, and obtained a few miserable plants, a 

 circumstance which admits of explanation if it is considered that 

 all dead organic substances are changed into humus by contact 

 with the roots of plants. De Greer endeavoured to raise plants 

 on strips of paper, cotton-wool, and sawdust ; he produced only a 

 few shoots, but regarded these as the product of nutrition from 

 the air, although it does not appear why, in this case, as 

 gigantic plants should not be developed as in good soil. He left 

 out of sight the partial decomposition of the organic matrix ; the 

 experiments moreover were imperfect, inasmuch as it was not 

 observed that in new sawdust plants not only would not grow, 

 but soon perished. 



Very recently the theory of the aerial nourishment of plants 

 has received some support from the communications of the 

 English traveller Darwin, which, it may be assumed, were brought 

 forward without a proper knowledge of the circumstances by 

 Liebig, Schleiden, &c. Darwin had before him especially the 

 cultivation of tropical countries — the culture of rice, sugar-cane, 



