Lycopodium complanatum and Lycopodium c lav a turn. 219 
at the tips of the horns of the crescent (see PI. XXII, Fig. 20), possibly 
indicating that the monarch condition, usually found, is a derived one. 
On the whole, the vascular arrangement obtaining in the roots of 
the young sporophytes resembles more nearly that found in those forms 
which have roots running through the cortex of the stem, such as L. Selago , 
differing however in the fact that the two xylem groups do not join up 
immediately behind the point where they join the stele of the stem, as is 
usually the case with the internal rootlets. It is clear, however, that 
the monarch condition occurring in certain parts of the root is brought 
about by the joining-up of the xylem on one side of the stele, and not by 
the abortion of part of the phloem, as appears to be the case in roots of 
certain of the Ophioglossaceae, e. g. O. vulgare , O. bidbosum , O. reti - 
culatum , which according to Van Tieghem 1 have diarch arrangement 
near their insertion, but only one of the lateral phloem groups is developed. 
B. The Foot Region. 
The foot of L. complanatum is a rounded structure covered with warty 
protuberances, which, providing a greater surface, enable it to withdraw 
more nourishment from the surrounding prothallus. Apparently the foot 
remains for a considerable time after the disappearance of the prothallus. 
In the sporophyte shown in PL XXII, Fig. 2, where the prothallus has 
almost entirely disappeared, the cells of the foot are unimpaired even at the 
periphery, and this, together with the fact that a small branch of the vascular 
tissue passes into it, would show that there is some possibility that it still 
acted as an absorbing organ. 
Treub 2 considers that the ‘embryonic tubercle ’ in L. cernuum , leaving 
the prothallus and leading a kind of independent existence, represents the 
foot of the embryo, and that the papillae on the foot of L. Phlegmaria 
correspond to hairs on this embryonic tubercle. The tuber of Phylloglossum 
corresponds in position and structure to the parenchymatous tuber of 
L. cernuum ; in both cases the tuber is composed of parenchymatous cells, 
and the superficial cells may develop root-hairs. Comparing the two, Bower 3 
remarks on the absence of a foot in Phylloglossum , but says * it is to be 
remembered that in this plant the place of the foot is to be taken, 
physiologically if not morphologically, by the stalk of the young tuber.’ 
The large parenchymatous cells, of which the foot of L. complanatum is 
mainly composed, are strongly pitted. The periphery is well defined in 
sections stained with haematoxylin, the walls appearing thicker than those 
of the internal cells on account of the thin layer of protoplasm which lines 
them. There are deep indentations between each cell, this again affording 
1 Van Tieghem, Traite de Bot., Part II, p. 1394. 
2 Treub, Ann. de Buitenzorg, vol. v, p. 128. 
3 Bower, Phil. Trans., 1885, Part II, p. 675. 
R 
