The Vegetative Anatomy of Molinia caerulea. 55 
almost solid central cylinder, whose diameter is about one fourth 
of the whole section, that the cord roots owe the remarkable 
tensile strength which makes the plant so difficult to tear from 
the soil. 
Sections of the cord roots generally show the cortical cells 
(Fig. 3, S) to have thick walls, prominent pits, and in the outer and 
middle zones circular outlines, this rounding off of the angles being 
associated with an increase in the number and size of the inter¬ 
cellular spaces; the same cells are also usually crowded with small 
starch grains. The wall thickening consists of cellulose, and both 
this and the starch are shown by their subsequent history to be 
forms of food reserve. The roots commonly function through three 
seasons. Examination of a specimen towards the end of its third 
summer, when the member was about two and a half years old, 
showed the process of digestion already commenced : 15 cm. from 
the rhizome the exterior was wrinkled and about one third of the 
tissue in question, with its contents, had disappeared ; 2 cm. from 
the rhizome digestion had begun but had made little progress. The 
food reserve thus remains in the cortex of the root until the latter 
ceases to function, when it is withdrawn. Young cord roots show 
this cortical thickening, so that the reserve is deposited early. 
During the active life of the root, the cortex with its abundant inter¬ 
cellular spaces, probably functions as an aerating tissue. Roots 
springing from shoots, where the development of the usual food 
reserve in the stem has been interfered with by the galls referred 
to later, are often unusually thick. From the old dead roots the 
thickened tissue and starch grains have disappeared, leaving the 
central cylinder surrounded by the endodermis and a loose detached 
sheath, the sclerenchymatous band, with a few remnants of 
incompletely digested cells (compare the tuberous internodes of the 
leafy stem). 
The structure of the fine roots shows in transverse section the 
same general plan as that of the cord roots, but adapted to its 
smaller dimensions. Again we find no cuticle, and a second row of 
good sized, thin walled cells supports the piliferous layer. Root 
hairs on these fine roots are rare and become common only on the 
thicker and older portions : the usual root hair region is absent, and 
the non-appearance of a cuticle suggests that the rootlets them¬ 
selves function as absorbing organs. Thus Molinia shows a 
reversal of the usual distribution of root hairs; they are absent 
from the youngest rootlets, appear first as we move into the 
