MANUEING m THEOEY AKD PEACTICE. 



117 



anuuonia by passing through sulphuric acid, and 

 then through a solution of carbonate of soda. These 

 conditions were proved to be adapted for healthy 

 growth by growing plants under exactly the same 

 circumstances, but in a garden soiL 



The prepared soil was also shown to be suitable for 



Pigs. 4, 5, and 6 represent plants of Wheat, Bar- 

 ley, and Oats grown in prepared soil, and suppUed 

 with a known quantity of combined nitrogen beyond 

 that contained in the seed sown. 



Pigs. 4, 5, and 6 show the development of the 

 three graminaceous plants, with an extraneous supply- 



Pig. 4.— 'Wleat. 



Kg. 6.— Oats. 



Pig. 5. — Barley. 



the purpose by the fact that plants grown in such 

 soil, and in the artificial condition of atmosphere, 

 developed luxuriantly, if only manured with sub- 

 stances supplying nitrogenous food. 



The accompanying diagrams show the character 

 and extent of growth attained under the conditions 

 in question, with Wheat, Barley, and Oats. 



Figs. 1, 2, and 3 represent plants of Wheat, Bar- 

 ley, and Oats grown in prepared soU, supplied with 

 no combined nitrogen beyond that contained in the 

 seed sown. 



of combined nitrogen, corresponding to the three 

 plants preceding them without any such supply. The 

 vigour and degree of growth attained may be taken 

 as sufficient evidence that the conditions of soil, 

 atmosphere, temperature, &c., were consistent with 

 active and healthy growth. 



The data obtained from these experiments clearly 

 proved that there was no assimilation of free nitro- 

 gen from the atmosphere, by the plants. 



They had vegetated, however, and in most cases 

 more than trebled the amount of carbon in the seed, 



