Anatomy of the Cone and Fertile Stem of Equisetum. 243 
E. maximum , and as the sporangiophores are more or less equidistant 
from one another, some of the incoming traces have to curve in order 
to attach themselves to a strand. The smaller the amount of xylem 
present at the fertile node the more numerous and the wider will be the 
parenchymatous meshes that persist; consequently, as a rule, the larger will 
be the number of incoming traces undergoing torsion, and the greater the 
degree of this torsion. 
Some of the traces of the cones of E. maximum diverge more or less 
steeply downwards; others pass out horizontally, while yet others traverse 
the cortex in an obliquely upward direction. Statistics of the divergence 
of the traces of different whorls are given in the appended table for Cones 
A and B. Owing to the greater number of whorls in the latter cone, 
whorls which would be numbered alike in both cones would not occupy the 
same relative position. So far as was possible whorls were selected 
occupying the same relative positions in both cones ; but the desirability 
of avoiding pseudo-whorls and whorls in which the cortex had been 
damaged, either in nature or by mounting, made it impossible to choose 
only whorls of exactly the same relative position. The whorls chosen 
were, counting from below upwards : Cone A, whorls 1, 4, 8, 12, and 17 ; 
for Cone B, whorls 1, 8, 14, 19, 26, and 27, the statistics for the last two 
being included under one head owing to their irregularity. These whorls 
have been lettered as Series A to E, from below upwards, so as to bring 
out the correspondence in their relative positions in both cones. 
Divergence of the Traces in the Cortex of Cones of E. maximum. 
Series. 
Cone. 
Extremes of divergence. 
Average divergence of traces. 
A 
A 
125/^-750/* downwards. 
312 /x downwards. 
A 
B 
275 /(-1,500/i downwards. 
200 /i upwards-175 n downwards. 
997-02 /t downwards. 
B 
A 
29-5/1 downwards. 
B 
B 
492 /t upwards-644 A 4 downwards. 
37-43 /t downwards. 
C 
A 
200 upwards-350 /i downwards. 
32-5/1 downwards. 
C 
B 
350 /t upwards-420 n downwards. 
80-91 /i downwards. 
D 
A 
300/1 upwards-75 fx downwards. 
72-9 /i upwards. 
D 
B 
140/* upwards-294/i downwards. 
53*63 /t downwards. 
E 
A 
28*75 M-300/i upwards. 
186*5 /t upwards. 
E 
B 
1 75/^-850/1 upwards. 
506 /t upwards. 
A study of this table gives rise to the following generalizations : 
1. In both the cones all the traces of the lowest series, Series A, 
diverge downwards, and though the individual traces vary greatly in the 
extent of their downward divergence, the average downward divergence 
of this series is in Cone A rather less, and in Cone B rather more, than ten 
times as great as the greatest average downward divergence of the other 
series studied. 
2. In both cones all the traces of the uppermost series, Series E, diverge 
upwards. 
3. In the intervening series, B-D, some traces pass out upwards, some 
