176 Gibson. — Contributions towards a Knowledge 
parenchyma. The xylem is normal, with one marginal 
protoxylem on each stele. 
40. Selaginella Kraussiana , A. Br. Baker’s Handbook, 
No. 120. 
This common garden species is one of the few that have 
received some attention from anatomists. Fundamentally it 
resembles X. delicatissima in structure, although it differs 
considerably morphologically. I have examined, in addition 
to .S. Kraussiana itself, the varieties Brownii and Stansfieldii. 
The mode of arrangement of the steles is quite similar to 
that shown in S. delicatissima. The epidermis is covered by 
a slightly warty cuticle, and is followed by one to two layers 
of sclerotic tissue. The cortex consists of large and delicate 
cells with abundant chlorophyll in the layers next the lacuna. 
The endodermal cells are not infrequently clustered so that 
two or three are embraced by one cuticular band (PI. X, Figs. 
47, 48). Some of the endodermal cells are very short, and are 
connected to the cortex by strings of short green parenchy- 
matous cells (PI. X, Fig. 46). Leclerc du Sablon (20) gives a 
figure of the transverse section of the stem of X. hortensis , a 
name by which S'. Kraussiana frequently goes. This figure 
seems to me to be inaccurate, and his description does not 
help much towards clearing up the vagueness which he 
complains of as surrounding the question as to what are the 
limits of cortex and vascular cylinder in Selaginella. More- 
over, his thesis (p. 21) cannot be maintained in view of the 
more recent researches of Vladescu and Strasburger. 
The pericycle is one layer thick, and there is one layer 
of sieve-tubes, absent opposite the protoxylem. One to 
two layers of parenchyma separate the sieve-tubes from 
the xylem. The phloem is not nearly so well developed in 
the primary (or older) stems. Where the steles fork at the 
branchings their pericycles are often connected by a reticulum 
of cells which show none of the characters of the ordinary 
trabeculae, although the cells composing the network may be 
partially or even completely cuticularized (PI. X, Fig. 50). 
Dangeard records an important observation with regard to 
