56 Bunting—The Structure of the Cork Tissues in 
older layers at the outer margin of a section, as in different 
species of Potentilla and in Fragaria indica. This arrangement 
is shown for Potentilla norvegica in Plate X, Fig. 1. In 
Fragaria indica, Potentilla chrysantha, P. geoides and P. alpes- 
tris, the alternation of pigmented uniseriate and unpigmented 
multiseriate layers is not so marked a feature, especially if 
material is obtained during the late autumn, winter or early 
spring months. After treatment with iodine and sulphuric 
acid, however, the annular condition is very clearly defined. 
This may also be the case with some species of Geum. In 
Geum atrosanguineum (Plate X, Fig. 2), quadrangular in- 
tercellular spaces are present. The alternation as to the 
size of the cells in the uniseriate layers is not so clearly shown 
in this species as in G. album, G. urbanum and G. rivale, but 
proof that the cell walls in the alternating layer are suberized, 
is obtained by the use of sulphuric acid and iodine. 
Group Agrimonice.—The following five species have been 
examined: Agrimonia Eupatoria, A. parviflora, Alchemilla pyre- 
naica, A. pubescens, Poterium Sanguisorba and Ace@na reptans. 
Intercellular spaces are present in the cork region ; and, as in 
some species of the last group, the cork is arranged in flattened 
compact uniseriate layers alternating with multiseriate layers 
of less compact cells. This condition is illustrated in Agv7- 
monia Eupatoria (Plate X, Fig. 3); Agrimonia parviflora 
(Fig. 4), and in Alchemilla pyrenaica (Fig. 5). As regards inter- 
cellular spaces, the most remarkable arrangement is found 
in Agrimonia parviflora. The cork region of this species 
may be described as follows. Immediately external to the 
cork cambium is a single layer of compact flattened cells 
with brown pigmented cell walls, while a brown pigment 
fills the cell cavities ; outside of this are three layers, the cells 
of which are so arranged as to form radiating beaded spokes. 
The inner two, of each triplet of cells in this zone, is of medium 
size, the external one is large, while between the radiating cell 
triplets are large intercellular spaces. The walls of each 
