OS ———— 
TRANSACTIONS OF SECTION B. 97] 
differing from the Graminee, the Cruciferze, the Chenopodiacese, and so on. But 
the same description of plant will exhibit very characteristic differences, not only 
at different stages of growth, but at the same stage in different conditions of 
luxuriance, as affected by the external conditions of soil, season, manuring, &c., 
but especially under the influence of different conditions as to manuring. 
The Rothamsted Field experiments have afforded ample opportunity for ob- 
servations of this kind ; and it has been quite evident that, in a series of comparable 
experiments with the same crop, depth of green colour by no means necessarily 
implied a finally greater amount of carbon assimilation; whilst we have long ago 
experimentally proved that the deeper colour was associated with relatively high 
percentage of nitrogen in the dry or solid substance of the herbage; and this obviously 
means a lower relation of carbon to nitrogen. 
Mentioning these facts to Dr. W. J. Russell, who has devoted so much attention 
to the subject of chlorophyll, he kindly undertook to make comparative determina- 
tions of the amounts of chlorophyll in parallel specimens, in which we were to 
determine the percentages of dry matter and of nitrogen, Accordingly, in June 
1882, during the period of active vegetation, Dr. Russell spent a day at Rothamsted 
for the purpose of collecting appropriate samples, which were taken from several 
differently manured plots of meadow-grass, wheat, barley and potatoes, respectively. 
The following table gives the results of some of these experiments; namely, the 
percentages of nitrogen, and the relative amounts of chlorophyll, in the separated 
gramineous and the separated leguminous plants in the mixed herbage of grass 
land; in specimens of wheat grown by a purely nitrogenous manure, and by the 
same nitrogenous manure with a full mineral manure in addition; and in specimens 
of barley grown by a purely nitrogenous manure, and by a mixture of the same 
RELATION BETWEEN NITROGEN ACCUMULATION, CHLOROPHYLL FORMATION, AND 
CARBON ASSIMILATION, 
(The figures in parentheses represent determinations in the not fully dried substance). 
Carbon assimilated 
| Nitrogen per Relative | per acre per annum 
| cent. in dry | amounts of | 
substance Chlorophyll | ’ 
Actual Difference 
Hay. lbs. lbs. 
Graminee . : 4 1:190 0-77 
Leguminose . : - 2-478 2°40 
WHEAT. 
Ammonium salts only : (1:227) 2-00 1,398 — 824 
Ammonium salts and mine- 
ralmanure .. : (0°566) 1-00 2,222 
BARLEY. 
Ammonium salts only i (1474) 3-20 1,403 ~ 685 
Ammonium salts and mine- 
ralmanure . : . (0-792) 1:46 2,088 
nitrogenous manure and mineral manure in addition. It is to be borne in mind that 
the specimens were collected while the plants were still quite green, and actively 
growing. It should be further explained that the amounts of chlorophyll recorded 
are, as stated in the table, relative and not actual; that is to say, the figures show 
the relative amounts for the individual members of each pair of experiments, and 
not the comparative amounts as between one set of experiments and another. 
It will be seen in the first place that the separated leguminous herbage of hay 
contained a much higher percentage of nitrogen in its dry substance than the 
