THE ACORN AND ITS GERMINATION 



13 



a thin, brown, wrinkled, papery membrane, which is its 

 own coat the seed-coat, or testa (fig. 2, ). The extent 

 to which the testa remains adherent to the seed, or to the 

 inner coat of the pericarp, and both together to the 

 harder outer coat of the pericarp, need not be commented 

 upon further than to say that differences in this respect 



FIG. 2. Sections of acorns in three planes at right angles to one 

 another. A, transverse ; u, longitudinal in the plane of the coty- 

 ledons (7) ; c, longitudinal across the plane of the cotyledons ; c, 

 cotyledons ; t, testa ; p, pericarp ; g, scar, and r, radicle ; pi, 

 plumule. The radicle, plumule, and cotyledons together consti- 

 tute the embryo. The embryonic tissue is at r and pi. The dots 

 in A, and the delicate veins in B and c are the vascular bundles. 



are found accordiug to the completeness and ripeness 

 of the acorn. 



Enveloped in its testa and in the pericarp, then, 

 we find the long acorn-shaped seed, which seems at 

 first to be a mere horn-like mass without parts. This 

 is not the case, however, as may easily be observed by 

 cutting the mass across, or, better still, by first soaking 

 it in water for some hours ; it will then be found that 



