62 
Rev. T. A. Jefferies. 
Successive sections show that the structure described, persists 
throughout the swollen part of the basal internode. When, 
however, the tapering becomes marked a transition sets in, and 
develops as we get higher up the internode until in the narrow 
green region (Fig. 5, B) we have the typical structure of a grass 
stem. The first change appears in the cortex where the cortical 
storage tissue is gradually broken up by a series of large lacunae, 
until in the upper part we have an interrupted cortex consisting of 
radial strands of thin walled cells, generally in single rows but 
occasionally in groups, crossing a large airspace. A corresponding 
change occurs in the centre where a space appears and gradually 
extends, while the wall thickening of the storage cells becomes less 
marked ; but this does not begin as low down as the large lacunae 
of the cortex. Finally we have the appearance of chlorophyll in 
the cortical cells adjacent to the subepidermal strengthening tissue, 
indicating photosynthetic activity in this region and explaining the 
greenness of this part of the stem. 
The food stored in these basal internodes is not used during 
the summer fruiting season but remains throughout the winter ; as 
soon, however, as the buds at their bases develop in the following 
spring they are found to be losing their contents: eventually nothing 
is left but the insoluble tissues forming the framework of the inter¬ 
node. These remains (Fig. 1, b.o.) consist of the outer wall of 
epidermis and sclerenchyma, the inner wall of pericycle, scler- 
enchyma, and vascular bundles, the scattered bundles, and a 
fringe of shrunken, dilapidated cell walls—all that remains of the 
dense storage tissue. In marked contrast with the functional 
swollen bases these empty shells collapse like straw between the 
fingers. The process of digestion by which these food reserves are 
used up is gradual, and on the same tussock we may find all stages 
of the process indicated by varying degrees of firmness, these 
differences being related to the varying stages of development 
reached by the subsidiary buds. For details of the actual break¬ 
down of the cells through digestion, see Woodhead (5). 
Since these swollen bases have to endure throughout the winter 
when the leaves lie dead, it becomes important to protect them 
from dangers which might enter through decaying elements, and 
this is secured by means of absciss layers. Now absciss layers 
are usually associated with leaf-fall, a phenomenon which is some¬ 
what rare in herbaceous plants. Hence absciss layers are uncommmon 
in such types, and in grasses especially few have been described: 
