TUB BATTLE OF LIFE. 101 



called a " legume." By these characteristics, not to mention 

 others, this group which comprises peas, heans, clovers, 

 vetches, sainfoin, lucerne, and other agricultural plants, 

 may be known. Some, such as peas and beans are annual, 

 others are perennial, and, as a rule, their habit or general 

 appearance is so strikingly different from that of the grasses, 

 that no one ever confounds them. 



Though containing a larger proportion of nitrogen in 

 their composition than the cereals, they are not specially 

 benefited by nitrogenous manures as the grasses are, and 

 this fact, observed when LeguminqsaB are grown alone as in 

 the bean or clover field, is no less marked than it is when 

 they are grown in association as in pasture land. At 

 Rothamsted, the largest proportionate quantities of Legu- 

 minosae occur on a plot to which mixed mineral manure 

 with potash is applied. Seasonal characteristics, even 

 when favourable to these plants, do not suffice to overcome 

 the injurious effects of some manures, as during many 

 years of varying character as to climate, they have been 

 practically banished from the ammonia plots. On the 

 whole their requirements are opposite to those of the 

 grasses, the conditions favouring the latter not being 

 anything like so propitious to the leguminous plants. 

 Thus the effect of nitrogenous manures as observed 

 on the experimental plots is to banish or reduce more 

 or less completely the Leguminosae, or so to favour 

 the growth of the grasses or certain of them, that the 

 Leguminosae are overpowered. On the other hand, 

 mineral manures, which are not by themselves very bene- 

 ficial to grasses, are very propitious to the growth of legu- 

 minous plants. Potash is especially favourable to these 

 plants, their predominance and produce is always enhanced 



