112 PROCEEDINGS OF THE COTTESWOLD CLUB 



supplied showed 5'233 grammes in the dry sub- 

 stance of the leaves and stem, and in 1884-5 

 certain pots showed 28*483 grammes, 33' 147 

 grammes, etc. 



(d) There was an entire absence of equality in the 

 pots. 



And finally it was clear ^/le peas had found some other 

 source of Nitrogen. 



These conclusions closed the year 1885. The problem 

 which now remained for solution was, where and how 

 did the peas obtain their Nitrogen ? 



Four hypotheses presented themselves, as indicating 

 the direction in which the solution might be found. 



I. — The Nitrogen, as in the case of Carbon Dioxide, 

 might be absorbed direct from the atmosphere. Boussin- 

 gault had satisfactorily settled this in the negative. 



2. — The larger amount of foliage and the length of the 

 growth period in the case of peas might enable them to 

 absorb a large quantitv of the combined Nitrogen of the 

 air, small as it is in percentage quantity. 



3. — The profound depth to which the roots penetrate 

 might enable them to reach hidden stores of Nitrogen. 

 Lavves and Gilbert had given some support to this 

 hvpothesis, but Hellriegel and Wilfarth's experiments 

 negatived this idea. 



4. — The Nitrogen might be obtained from the soil 

 indirectly, the soil obtaining it by absorption of Meteoric 

 Nitrogen, or by other well known causes, whereby it is 

 set free in the soil. The method of obtaining it on the 

 part of the peas was not explained by this hypothesis. 



Atwater, in the United States, had grown peas which 

 gave twelve times more Nitrogen than had been given 

 them. 



E. Wolff had cultivated oats, potatoes, and four species 

 of Leguminosse, and found in the two former less 

 Nitrogen than was suppHed, but in the latter very 



