28 Saxe l by. — The Origin of the Roots in Lycopodium Selago. 
in connexion with each phloem group in turn, I, II, III, I, &c. Where the 
stem branches the roots pass from the cortex of the smaller branch into the 
cortex of the main branch, and the bases of roots were seen close to 
the point of dichotomy of the vascular strand of the stem, showing that the 
roots arise from each of the two vascular strands while the latter are still 
enclosed in one cortex. It was found also, that where the stem has grown 
obliquely to the ground plane, the roots are all in one half of the cortex ; 
where the stem grows upright, the roots are arranged in the cortex on 
all sides of the stele ; Fig. 7 shows eleven roots lying almost entirely in one 
half of the cortex of the stem. A section about a centimetre higher up the 
same stem showed roots all round the stele, but between the two points of 
section the stem had curved upwards. The lower section, i. e. the one 
figured, is cut from a part of the stem just above the ground, above the 
highest point at which a root appears outside the stem. In one case 
of a young plant from a bulbil, the second root, coming from the part of the 
stem surrounded by bulbil leaves, was seen to run transversely across the 
stem and turn slightly upwards, so that in a transverse section of the stem 
the meristematic apex of the root was cut vertically. Here, however, the 
bulbil was fixed in the ground with its base pointing obliquely upwards. 
These facts I consider prove that the course followed by the roots through 
the cortex depends upon the position of the stem relative to the ground. 
Bruchmann 1 in his earlier paper mentions that the course of a root relative 
to the stem is altered where the latter undergoes gradual rotation, but 
he states that moisture and darkness appear to be the only factors which 
cause this change. I should ascribe it, in all the examples of L. Selago 
mentioned above, rather to the force of gravity, but the other conditions re- 
ferred to may play some part, since the roots only appear on a level with 
the soil. Jones 2 mentions the fact that the roots only emerge where the 
stem is growing obliquely, but does not enter into detail, or give his con- 
clusions as to its cause. 
A large proportion of the roots present in any stem are found with 
their meristematic apices still embedded in the cortex of the flatter. 
Strasburger 3 states that the roots often dichotomize before leaving the 
cortex of the stem, but I have not observed this in L. Selago , although one 
root was seen dividing when only two-thirds free from the cortex. For 
L. dichotomum , however, Strasburger’s statement holds good, and two root 
bundles may often be seen enclosed in one cortical sheath. 
The lowest root in the young plant grown from the bulbil, that is the 
first formed root, from the outside appears to be directly continuous with 
the central strand of the bulbil. Strasburger, 4 however, refers to the fact 
that in reality it arises from the side of the stele and at once directs itself 
1 Bruchmann (a), loc. cit., p. 527 and following. 2 Jones, loc. cit., p. 22. 
3 Strasburger (<?), loc. cit., p. no. 4 Strasburger (c), loc. cit., p. 114. 
