OTHER METHODS OF OBTAINING FOOD 207 
grow from seed with fair rapidity, the root of the seedling 
attaining a length of an inch in two or three days. Shortly 
after penetrating the soil, the main root puts out secondary 
branches, which make their way parallel to the surface. 
As they grow chiefly in woods or among herbage, they 
speedily encounter the roots of other plants, and on contact 
being made between one of these root-branches and a root 
of a suitable host, a curious sucker-like body is developed 
at the point of con- 
tact (fig. 99). This is 
a kind of parenchy- 
matous cushion, which 
partly surrounds the 
host, and from the 
inner side of its con- 
cavity certain absorp- 
tion- cells grow out 
and penetrate into 
the former, pushing 
their way until they 
reach the centre of 
the invaded root (fig. 
100). These absorbing 
neously spoken of as Kerner.) 
roots. They cannot 
properly be so called, as they are developed from the cortex 
of the rootlet, and not, ag root-branches are, from the tissue 
of the pericycle. They are best spoken of as haustoria, 
a term which is purely physiological, and carries with 
it no anatomical significance. 
While the root is setting up this relationship with a host 
plant, the shoot of the seedling is growing normally. Its 
leaves and other subaerial parts are well developed and 
discharge their appropriate functions. The plants would 
not be recognised at all as in any way parasitic without 
an examination of the subterranean parts. They absorb 
