66 THE NATURAL HISTORY OF BRITISH GRASSES. 
to its feeding properties, which places it among grasses of 
superior quality, yet cattle will not eat it if they can pos- 
sibly avoid doing so, and hay is always poor in which it 
occurs, which is not to be wondered at when the lop, for 
the most part, elects to grow in the most impoverished 
soils. 
Bromus commutatus we can only view as a variety of B. 
mollis. Its situation is that of low damp irrigated mea- 
dows, in which the mollis is quite exceptional, though, when 
it does occur, it assumes the drooping habit of the commu- 
tatus, and offers many intermediate states. Now, as we 
have watched the laying out of poor pastures as irrigated 
meadows, we have observed that two or three years is often 
capable of changing the B. mollis, which was before alone, 
into commutatus. Of course it may be considered that this 
was in virtue of that law of substitution of one species for 
another which universally occurs on a change of soil, but 
we incline to think that much of this where it occurs is due 
not merely to this cause, but to real change of form, as the 
result of an alteration of condition and circumstance ; and, 
as regards the grass under consideration, our chain of evi- 
dence is nearly complete in establishing this position, when 
it is stated that the B. commutatus, from the irrigated mea- 
dows, most certainly in cultivation im my experimental 
garden, has resulted in some fine examples of B. seculinus, 
a form not before known there, and therefore not liable to 
have led me into error, as might be the case where the 
different varieties are wild natives. 
That B. arvensis, and perhaps other forms, may by culti- 
vation be shown to be varieties of an annual grass, of which 
B. mollis is the common type, 1s an idea which seems to be 
countenanced by the protean forms of mollis and its con- 
geners. 
B. erectus is a perennial brome, very partial to limestone 
soils, and is one of the commonest grasses on the poor thin 
oolite brashes, extending along the whole of the Cotteswold 
chain of hills, from Bath to Chipping Campden; it is no 
