1262 
MESSRS. J. B. LAWES, J. H. GILBERT, ARD M. T. MASTERS, 
out ammonia), in 1869, and each year since, Lathyrus did not contribute 5 per cent, 
to the produce in either 1862, 1867, or 1872, but that it did so in 1877, that 
is some years after the change. The plant yielded more than 5 per cent, to the 
produce in each separation-year on plot 7, where the mixed mineral manure, 
including potass, was applied alone every year. And it did so in 1862 and 1867, but 
not afterwards, on plot 8, to which the same mixed mineral manure, including 
potass (in considerable excess), was applied for six years, to 1861 inclusive, but 
■without potass in 1862 and afterwards. 
The actual percentage of Lathyrus in the total herbage was increased from 0'23 in 
the first, to 6'56 in the last separation-year on plot 6, where the ammonia-salts were 
applied in the earlier years, and the potass manure in the later. It diminished from 
8 ’76 to 2'37 per cent, on plot 8, which received potass during the earlier, but not 
during the later years ; and on plot 7, where the mineral manure including potass 
was applied every year, Lathyrus contributed 13'51 per cent, in the warm moist season 
of 1862, 6'78 per cent, in the cold and changeable season of 1-867, 36*68 per cent, in 
the variable season of 1872, and 12T1 per cent, in the tardy spring of 1877. It also 
increased up to 9'22 per cent, in 1877 on plot 16, where the smaller quantity of 
nitrate with the mineral manure, including potass, was every year applied. It has 
likewise increased in a very remarkable degree, in recent years, on plot 15, where 
nitrate of soda alone was applied up to 1875 inclusive, but the mixed mineral manure, 
including potass (without nitrate), each year since. It is obvious that potass manure 
has remarkably increased the development of this species, whilst it has not done so in 
the case of either of its three allies. 
Somewhat detailed reference has already been made to this result in the section 
relating to plot 7 (Part I., p. 307, et seq.); and the subject will come up again when 
discussing the botany, and again when discussing the chemistry, of that plot. But it 
may here be remarked that, of the four leguminous species which have been considered, 
the Lathyrus feeds by its adventitious roots very much more than the rest in the 
surface-soil; that the supplied potass descends comparatively little into the sub-soil; 
and that the nitrogen of the surface-soil where this leguminous plant has so remarkably 
developed, has diminished in a greater degree than on any other plot. It would 
appear that under the influence of the liberal potass supply, the plant has been enabled 
to obtain the large amount of nitrogen it requires in a greater degree from the accu¬ 
mulated stores within the surface-soil. 
It seems probable, from the foregoing data, that some of the fluctuations in the 
amount of produce yielded in different seasons by this plant may be explained by its 
peculiar habit of growth. Its Underground development, either of root or stock, is 
relatively small, as compared either with that of most of the grasses or with that of 
Lotus and the Clovers. On the other hand, its above-ground growth, its creeping 
stems and erect branches, insinuating themselves between their competitors, and 
clinging to them by means of their tendrils, &c., constitute differences which may go 
