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 without 



