464 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



(Liebig, however, failed to understand the role of soil as a source of 

 nitrogen for plants, and the fixation of atmospheric nitrogen by bacteria 

 was not then known.) 



Once it was recognized that the function of the soil in the economy 

 of the plant is to furnish certain chemical elements, as well as water, 

 it was but natural to attempt to supply these elements and water 

 independently of soil. The credit for initiating exact experimentation 

 in this field belongs to the French chemist, Jean Boussignault, who 

 is regarded as the founder of modern methods of 

 conducting experiments in vegetation. 



Boussignault, who had begun his experiments on 

 plants even before 1840, grew them in insoluble 

 artificial soils: sand, quartz, and sugar charcoal, 

 which he watered with solutions of known com- 

 position. His results provided experimental veri- 

 fication for the mineral theory of plant nutrition 

 as put forward by Liebig, and were at once a demon- 

 stration of the feasibility of growing plants in a 

 medium other than a "natural soil." This method 

 of growing plants in artificial insoluble soils was 

 later improved by Salm-Horstmar (1856-60) and 

 has been used since, with various technical im- 

 provements, by numerous investigators throughout 

 the world. In recent years, large-scale techniques 

 have been devised for growing plants for experi- 

 mental or commercial purposes in beds of sand or 

 other inert solid material. 



After plants were successfully grown in artificial 

 culture media, it was but one more step to dispense 

 with any solid medium and attempt to grow plants 

 in water to which the chemical elements required 

 by plants were added. This was successfully 

 accomplished in 1860 by Sachs and about the 

 same time by Knop. To quote Sachs directly: 3 



In the year 1860, I published the results of experiments 

 which demonstrated that land plants are capable of ab- 

 sorbing their nutritive matters out of watery solutions, without the aid of soil, 

 and that it is possible in this way not only to maintain plants alive and growing 

 for a long time, as had long been known, but also to bring about a vigorous increase 

 of their organic substance, and even the production of seed capable of germination. 



The original technique developed by Sachs for growing plants in 

 nutrient solutions is still widely used, essentially unaltered. He ger- 

 minated the seed in well-washed sawdust, until the plants reached a 

 size convenient for transplanting. After carefully removing and 



Figure 1.— Water-culture 

 installation employed 

 by the plant physiologist 

 Sachs in the middle of 

 the last century. 



(Reproduced from Sachs, 

 Lectures on the Physi- 

 ology of Plants. Clar- 

 endon Press, 1887.) 



von Sachs, Julius. Lectures on the physiology of plants, p. 283, Clarendon Press, Oxford, 1887. 



