98 COLIN" CLOUT'S CALEHDAK. 



like these snapdragons, you will find no two species 

 colored alike, and most species wonderfully spotted 

 and dappled with mingling yellow, blue, and purple. 

 Once more, the leaves vary immensely : each kind hits 

 out a separate type for itself, and adapts it exactly to 

 the soil and sunlight of its particular situation. 



"With such universal plasticity of constitution as this, 

 it is easy to understand how the parasitic habit could 

 have been acquired and maintained. The little eye- 

 bright which grows so abundantly on roadside commons 

 is still, perhaps, in the earliest stage of the practice. Its 

 flowers are most like the blue speedwells, though much 

 streaked with red, white, and purple ; and its roots only 

 suck nutriment slightly from the thin rootlets of the 

 grasses about it. It does far less harm in meadows than 

 yellow-rattle, and is hardly recognized by farmers as a 

 distinct enemy at all. Next to it, apparently, come the 

 two red-rattlesmarshy plants with much more special- 

 ized flowers, and queer fleshy jagged leaves ; they also 

 do but little practical damage, because they frequent 

 swamps, and feed only at the expense of the rank grass 

 in water-logged patches of meadows. Then come the 

 still more parasitical cow- wheats, very injurious to stand- 

 ing corn, but happily rare in England except on the 

 south-east coast. In Norfolk, purple cow- wheat is a 

 regular pest, one of the worst possible cornfield weeds, 

 and very difficult to eradicate, since it sheds its seeds 

 before the harvest is reaped. This plant shows in an 

 incipient form the common tendency of advanced 

 parasites to lose the greenness of their leaves ; and 

 when once a weed has finally reached that depth of 

 degradation it must feed forever in future upon the 

 juices of its host, having no chlorophyl of its own with 

 which to assimilate starches for itself from the air. Last 



