Janhaky 2, 1903.] 



SCIENCE. 



21 



stroked by his method of removing fixed 

 nitrogen. In this connection it is of in- 

 terest to refer again to the position on the 

 nitrogen question occupied alone by Ville. 

 It can readily be understood that, in the 

 large apparatus employed by this investi- 

 gator, the chances for complete steriliza- 

 tion were very remote, especially since no 

 particular attention was paid to this point. 

 Microbes from the soil could easily have 

 found their way into his large case through 

 dust or otherwise, and in the presence of 

 organic matter arising from the seeds and 

 the roots of the plants, could, in a short 

 time, become active in fixing the free ni- 

 trogen of the air. The contention of Ville 

 that, in his experiments, free nitrogen of 

 the air was assimilated by plants may, 

 therefore, have been sound. 



But to return to the line of thought 

 broken by this digression, Wilfarth re- 

 ported some important gains in nitrogen 

 by lupines grown in pots with four liilos 

 of nitrogen-free sand on addition of a 

 measured quantity of soil infusion con- 

 taining not more than seven tenths of a 

 milligram of fixed nitrogen. The yields 

 are as follows: 



With Soil Infusion: 



No. 3. 44.73 grms. dry matter with 1.099 grmg. 

 nitrogen. 



No. 4. 45.62 grms. dry matter with 1.156 grms. 

 nitrogen. 



No. 5. 44.48 grms. dry matter with 1.194 grms. 

 nitrogen. 



No. 8. 42.45 grms. dry matter with 1.337 grms. 

 nitrogen. 



Without Soil Infusion: 



No. 9. 0.918 grms. dry matter with 0.0146 

 grms. nitrogen. 



No. 10. 0.800 grms. dry matter with 0.0136 

 grms. nitrogen. 



No. 11. 0.921 grms. dry matter with 0.0132 

 grms. nitrogen. 



No. 12. 1.021 grms. dry matter with 0.0133 

 grms. nitrogen. 



By the sole employment of a small quan- 

 tity of soil infusion containing an infin- 



itesimal aiiiount of combined nitrogen, in 

 pots holding about eight pounds of sand, 

 the plants made an average gain in dry 

 matter of 42.9 grams, and in nitrogen of 

 1.18 grams over the same kind of plants 

 grown under the same conditions without 

 this addition. This remarkable result was 

 surely worthy of the general interest which 

 its publication evoked. 



Numerous experimenters all over the 

 world at once began to pay attention to the 

 little tubercles, and they were investigated 

 from aU points of view. Their morphol- 

 ogy was studied by Prank, Laurent and 

 others. For this purpose Frank, as well 

 as Laurent, grew plants partly in water 

 culture with the production of root tu- 

 bercles. Since their labors belong to the 

 domain of biology this simple reference to 

 them here will suffice. 



The results of all investigations from a 

 chemical standpoint verified the conclu- 

 sions reached by HeUriegel and Wilfarth. 

 But, in addition to this, a great many new 

 facts bearing upon this subject were -ob- 

 tained. Breal analyzed the nodules . of 

 various legumes and found that the con- 

 tent of nitrogen in the dry matter varied 

 from three to seven per cent., and was 

 higher than that of any other part of the 

 plants excepting the seeds. This fact is 

 significant. 



Breal also obtained results similar to 

 those of HeUriegel and Wilfarth by ger- 

 minating peas between moistened filter 

 papers, inoculating the roots, after they 

 had attained the length of a few centi- 

 meters, with a needle which had been 

 plunged into a tubercle, and then growing 

 the plants in nitrogen-free sand containing 

 the necessary mineral ingredients of plant 

 food. 



This investigator also grew peas in 

 water culture. After germinating seeds 

 between moistened filter papers as before, 



