The History of a Field newly laid down to Permanent Grass. 21 
otherwise available to tliem in the combined form. It further 
seemed probable, that the growth and crop-residue of certain 
plants favoured the development and action of special organisms. 
It is admittedly not yet understood, either in what way the 
lower organisms affect the combination, or in what way the 
higher plants avail themselves of the nitrogen thus brought into 
combination. 
Thinking that such results, if confirmed, were of very great 
significance, and the conclusions to be drawn from them were of 
fundamental importance, we decided to institute experiments at 
Rothamsted on somewhat similar lines. An initiative series 
has already been undertaken. At present, however, the ana- 
lytical results are not complete ; but, so far as they go, they seem 
to iudicate the probability that there has been some gain of 
nitrogen beyond that supplied in the combined form, in the soil 
and in the seed sown. It is remarkable, however, that .in the 
experiments of Hellriegel and Wilfarth they have not succeeded 
in enhancing the assimilation of nitrogen by red clover by such 
means. The plants with which their most striking results have 
been obtained are peas and lupins ; and it is with peas that the 
indications have been obtained at Rothamsted. Should it be 
finally established, that such an action does take place in the 
case of certain plants, though not in that of others, it is obvious 
that part at any rate of the gain of nitrogen by the soil support- 
ing the mixed herbage of grass-land, may be due to the free 
nitrogen of the air brought into combination under the influ- 
ence of the action supposed. 
The Botany of the Meadow. 
Botanical separations in samples of the herbage have not 
been undertaken ; but careful examinations of its character have 
been made from time to time by Mr. J. J. WUlis, who conducts 
the botanical work of the Rothamsted experiments ; and Table 
VIII. (page 22) gives the results of his estimates, made in 
November 1868, and in eleven recent years a short time before 
cutting, of the five most prominent grasses, the four most 
prominent leguminous plants, and the four most prominent 
miscellaneous or w^eedy species. It will be seen that, with the 
exception of 1877 and 1884, the recent seasons were 1876-88. 
Before referring to the results relating to recent years, atten- 
tion should be directed to the notes taken at the earlier period, 
namely in 1868. It was then stated, that Dadylis glomerata 
(cock's-foot) was plentiful, Poa pratensis (smooth-stalked meadow- 
grass) abundant and luxuriant, Lolium perenne (perennial rye- 
