A. W. Hill 
7 i 
The largest and oldest spines are in each case situated nearest 
to the nodes of the stem, whilst they are quite small where the 
two lobes come in contact, usually at a point about two-thirds of 
the way up the internodal cell. And since the spines from the 
ascending lobe bend sharply upwards, and those from the descend¬ 
ing lobe bend downwards in an equally striking manner, the tips of 
the spines in the young state tend to meet one another and give 
the section of a young internode a peculiar and very characteristic 
appearance (Fig. 69). 
An examination of an older internode (Fig. 70) shews the spines 
in a further state of development and considerably elongated, so 
that they have over-lapped each other and become interlaced, thus 
forming a tangled barrel-like figure of spines, which makes a dense 
protective covering to the young internodal cells. 
With the increasing age and consequent lengthening of the 
main internodal cells, the spine-bearing nodal cells of the cortex 
become separated from one another and the spines which are 
borne in groups of three tend to lose their characteristic arrange¬ 
ment. 
The Figs. 71, 72, and 73, shew old nodal cells of the cortex in 
longitudinal and transverse section and also in surface view; they 
are slightly different to the figures previously published in 
Rabenhorst. 
Fig. 71 .—Longitudinal section 
of a fully developed cortical 
node with spines. The starch 
in the nodal cell (n) and head¬ 
cell (k) indicated by shading. 
The small nodal cell («) has 
a swollen head cell ( k ), on eithe 
Fig 72 .—Transverse section of the 
cortex shewing a nodal cell («) with 
head-cells ( k ) and group of spines. 
Shading indicates occurence of 
starch. 
produced by a tangential division 
• side of which two or sometimes 
