474 MB. J. B. i,\\\i:s. DB. GILBERT, WD hi;. PUGH 



in which the roots develope luxuriantly*. Yet this water does nol evaporate w freely 

 as it otherwise would do, owing to the inward curve of the top of the pan. which also 

 serves to protect the roots distributed through the water from the direct action of sun) 

 All the com lit inns of -row ill are thus attained with a minimum of evaporation from all 

 sources excepting through the plant itself; and a drier atmosphere is maintained. ' 

 sequently evaporation through the plant is favoured, and hence the conditions are pro- 

 vided for a constant supply to the plant of all the mineral and ga ubstana 

 solution in the fluid of the soil and pan. 



E. — Final preparation of the Soil, Ash, and Pot. for the Plant. 



The soil and ash. each prepared as described in the foregoing subsections, and the 

 pot, also as described above, were simultaneously heated to redness; and the Boil and 

 ash, whilst red-hot, were mixed together in the red-hot pot, which was placed upon a 

 red-hot brick over sulphuric acid. The pot and contents were then covered with a large 

 glass shade, and left to cool. 



The soil, as in its former preparation, was heated in a cast-iron muffle, from which it 

 was removed with a small iron shovel adapted to the purpose, and heated to redness 

 before being used. 



Four or five pots were heated together, one inside the other, the top and bottom ones 

 of which almost invariably broke, either on the application of the heat, or on removal 

 from the fire ; so that only about half of those operated upon were finally available for 

 use. 



From 2^ lbs. to 3 lbs. of ignited soil were put into each pot ; but in the experiments 

 of the second year, 1858, the lower part of the pot was first filled, to the depth of about 

 1 inch, with very coarsely broken-up red-hot flint. In 1857, about 14 grammes of ash, 

 and in 1858 about 7 grammes only, were used for each pot. The greater portion of the 

 ash was mixed with the lower layers of the soil ; but some was distributed through the 

 whole of it. 



After cooling down sufficiently, the shade was removed, and about 500 cub. centims. 

 of distilled water, prepared as described in subsection C, were added to the soil of each 

 pot, this being as much as it would absorb. Then, after a lapse of ten to twenty hours, 

 the seeds or plants were put in. 



F. — The Seeds and Plants taken for experiment. 



In all the experiments recorded, the plants were grown directly from seed sown in the 

 soils prepared as above described. 



In every case, seed of the best quality was taken, which was kindly presented to us 

 for our purpose by the Messrs. Thomas Gibbs and Co., of Half-Moon Street. Piccadilly, 



* See Table, and general remarks at p. 521 ; also notes of root-development of "Wheat No. 6 (1S57), p. 553, 

 Wheat No. 1 (1S5S), p. 560, and Wheat No. 9 (1S5S), p. 569. 



