The Effect of Organic Matter on the Growth of 
various Water Plants in Culture Solution, 
BY 
W. B. BOTTOMLEY, M.A., Ph.D„ 
Professor of Botany at King's College . , London. 
With Plate XVII. 
T HE importance of organic manures in agricultural operations is a well- 
recognized fact* and a considerable amount of evidence has been 
accumulated by the author in support of the view that such organic manures 
are of direct importance in the nutrition of the plant, quite apart from their 
indirect effect in altering and improving the physical condition of the soil 
and in providing food for soil bacteria. It has already been shown that 
plants of Lemna minor will not grow and flourish normally in solutions 
containing mineral nutrients only, and that the addition to such nutrient 
solutions of small quantities of organic substances obtained from decom- 
posing vegetable matter , 1 from cultures of nitrogen-fixing organisms, and 
from nucleic acid and its derivatives 2 which the author has found can be 
extracted from raw peat , 3 enable the plants to multiply rapidly and retain 
their healthy appearance. 
It has also been shown 4 that the failure of a pure inorganic solution to 
support normal growth in these plants is not due to an unsuitable balance 
of nutrient materials, for similar results were obtained with more than one 
solution in common use among experimenters with water cultures ; while 
trials carried out with water of the pond in which the plants were growing 
showed that in this medium they maintained their normal health and vigour, 
although their rate of multiplication was retarded as compared with that in 
the artificial nutrient solution, presumably owing to the lack of any large 
quantities of the essential inorganic materials in the pond water. The 
organic matter, which this water contained to the amount of nearly five 
hundred parts per million, enabled the plants to grow healthily throughout. 
1 Bottomley, W. B. : Proc. Roy. Soc., B., vol. lxxxix, pp. 481-507 (1917). 
2 Ibid., vol. xci, pp. 83-95 (1919). 
3 Ibid., vol. xc, pp. 39-44 (1917). 
4 Ibid. : Annals of Botany, vol. xxxiv, No. cxxxv (1920). 
[Annals of Botany, Vol. XXXIV. No. CXXXV. July, 1920.] 
