Saxelby . — The Origin of the Roots in Lycopodium Selago. 27 
first radially, forming several radial rows of cells, the number varying from 
about three to six, then tangentially causing outward growth of the 
plerome. Since, however, the periblem curves round the plerome, the 
radial divisions of the former are in the same direction as the tangential 
divisions of the latter. My observations thus agree with Bruchmann’s 
conclusions, stated in his earlier work, that the roots grow without 
apical cells. 
The Course of the Roots through the Cortex. 
L. Selago differs from L. inundatum in the point at which the roots 
arise. According to Bruchmann’s first treatise, the roots of the latter species 
appear at the top of the stem before the youngest leaves, seldom later as in 
other Lycopods. In his later work , 1 however, he says they sometimes 
begin to form before the youngest leaf-trace arises, but mostly afterwards. 
Jones 2 merely states that the roots of L. Selago arise quite high up 
the stem, even above the point where the latter has branched, while 
Strasburger 3 finds internal roots of the same species usually appearing 
above the first dichotomy. I find roots arise in this species only below the 
point of origin of several leaf-traces. In an old plant they were found still 
at a fairly young stage, near the apex of the stem which bore sporophylls, 
though below the youngest leaves. 
With reference to the course taken by the roots through the cortex in 
L. Selago, Bruchmann 4 states that the root grows downwards in the plant, 
parallel to the vascular cylinder, and, as soon as it finds a suitable position, 
it breaks through the remaining layers of the cortex and passes out into 
the ground. Van Tieghem 5 mentions that the root, after passing vertically 
down through the cortex, escapes at the level of the ground. I find in the 
same species the roots arising at the apex of an upright stem pass first 
obliquely, then directly down, through the middle cortex until the surface 
of the soil is reached and a bend in the stems occurs. No roots appear 
outside the stem above this point. Numerous roots may come off* from 
the stem stele below the highest point at which a root breaks through to 
the outside. 
It was stated above that the roots are each connected with one phloem 
group : the two xylem groups adjacent to the same become connected with 
the root xylem at a later stage. The roots, however, do not arise from each 
phloem group in a definite order. For instance, if we name the phloem 
groups of the stem I, II, III, then in one series of transverse sections down 
the stem it was seen that the roots arise from I, then II, then I again, not 
1 Bruchmann ( b ), loc. cit., p. 75. 2 Jones, loc. cit., p. 22. 
3 Strasburger (c), Eine Bemerkung iiber Lycopodiaceen. Bot. Zeit., 1873, p. 109. 
4 Bruchmann ( 3 ), loc. cit., p. 101. 5 Van Tieghem, loc. cit., p. 557. 
