THE BATTLE OF LIFE. 95 
particular manner distinct from that of the other tenants 
of the plot, yet it is found that individual grasses, and 
even members of the same genus, vary very much 
among one another. 
It is instructive to compare the different tendencies of 
the two most generally prevalent grasses, Festuca ovina 
and Agrostis vulgaris. As to structural endowments 
they would seem to be not unfairly matched, but the 
Festuca is conspicuously worsted on the plots highly: 
dressed with nitrogenous manures, while the Agrostis is 
befriended by them, and its vigor and tufted habit are 
increased. Poa trivialis and Holcus lanatus afford con- 
trasts of a similar character, the Poa being largely in- 
creased by nitrate of soda, while the Holcus is similarly 
acted on by ammonia salts. Of the same character are 
the differences observable between Agrostis vulgaris, 
which is influenced by ammonia salts, and Holcus lana- 
tus, Avena pubescens, and Avena flavescens, which are 
especially acted upon by nitrate of soda. Very marked 
contrasts between species of the same genus also occur, 
as between such structurally very closely related plants 
as Poa trivialis, and P. pratensis, and between the 
three species of Avena. On the contrary, Bromus mollis 
and Poa trivialis are so far similar that nitrate of soda 
is very favorable to them both. Poa pratensis and 
Agrostis vulgaris concur in their liking for ammonia 
with mineral salts, while they manifest opposite tenden- 
cies with regard to nitrate of soda; Poa pratensis not 
being favored by it, while the Agrostis is so conspic- 
uously. , 
These are only a few of the remarkable contrasts and 
similarities that an inspection of the Rothamsted records 
brings out. Perhaps the most striking point in this 
connection is the opposite tendency manifested by differ- 
ent grasses in reference to the action of ammonia salts, 
and of nitrate of soda respectively, with or withont 
