PROCEEDINGS OE THE COTTESWOLD CLUB 107 



a layer of three centimetres of rough pieces of quartz, 

 which had been heated to redness, and then well washed. 

 Then a pad of unglazed cotton wool : and lastly the soil 

 composed of the sand referred to. 



It is at once apparent that this soil contains nothing 

 whatever (if we neglect the mere traces of the substances 

 mentioned above) that can contribute to the food and 

 growth of any vegetable life. 



This sand was, however, previously watered with a 

 nutritive solution hereinafter described, to bring it into a 

 suitable condition of " tilth," found to be most advantage- 

 ous for the plants, and to provide the necessary food 

 for the plants sown. Each jar held about 4 kilogrammes 

 of this soil. 



The so called nutritive solution employed was a mix- 

 ture of 



This mixture had been found by long experience to be 

 the one best suited to the amount and area of the sand in 

 each jar, and to the healthy growth of the experimental 

 plants. The three first ingredients of the above mixture 

 may be passed over without remark: it is the fourth the 

 calcium nitrate, which is the determinative factor in the 

 experiments, as it is the only one containing any nitrogen. 

 No less care was exercised in the selection of the seeds to 

 be grown. Each seed was weighed, and fair average 

 specimens were selected, neither the heaviest nor the 

 lightest, but those of a mean weight. The germinating 

 power was also previously tested, so that those only were 

 taken which shewed fair average character. In each pot 

 was sown a double quantity, so that when they appeared 



