UTILIZATION OF ATMOSPHERIC NITROGEN 303 



in the cases last mentioned, but only after being converted into a 

 more highly oxidized form by the activity of ferric hydroxid. 



It seems to be established that ferric hydroxid at ordinary 

 temperature, that is, from 15 to 25, develops a catalytic 

 influence on ammonia and ammonia salts, and that under this 

 influence an assimilable form of nitrogen is developed in the soil 

 independently of the activity of nitrifying ferments, even in the 

 presence of large quantities of thymol or of corrosive sublimate 

 up to two per cent., quantities which are entirely sufficient to 

 inhibit the action of the ordinary nitrifying ferments. The am- 

 monia of the air and of the soil may thus be converted into nitrous 

 acid by the oxidation produced under the influence of the catalytic 

 activity of ferric hydroxid. 



266. The Utilization of Atmospheric Nitrogen by Other Plants 

 Than Legumes. The evidence which seeks to establish the fact 

 that other plants than legumes are capable of utilizing atmos- 

 pheric nitrogen is not wholly conclusive. Theoretically, it seems 

 a rather strange provision of nature that only plants of the legu- 

 minous family should have the faculty, either symbiotically with 

 nitrifying organisms or directly, to utilize atmospheric nitrogen 

 as a source of plant food. Nevertheless, the greater number of 

 carefully conducted experiments in which all sources of possible 

 error are excluded, have led, as a rule, to negative results with 

 other plants, so that it can scarcely be affirmed with any scientific 

 certainty that this property of plants is a general or even a com- 

 mon one. On the other hand, in a review of this subject in con- 

 nection with research work, Jamieson has reached the conclusion 

 that the property of utilizing atmospheric nitrogen belongs to 

 many other forms of plants besides the legumes. 66 In this re- 

 port Jamieson undertakes to establish the fact that the legume 

 tubercle theory is untenable, and that the nitrogen of the air is 

 directly utilized by plants in general. In all the plants examined 

 by him, structures which absorb free nitrogen from the air and 

 transform it into the organic state were found. Seventeen forms 

 of plants of widely different character are said by Jamieson to 

 have been examined and found to possess the property indicated. 



66 Report of the Agricultural Research Association of the North- 

 eastern Counties of Scotland, 1905 : 16. 



