384 Boodle. — On some points in the 
reduction, which takes place in rootlet-bases of Botrychium 
Lunaria ), one would obtain the structure of the monarch root 
of Ophioglossum vulgatum and with the orientation that it has 
at its junction with the stem-bundle. 
The first root of seedlings of Botrychium virginianum is of 
typical diarch or triarch structure 1 , and this point may be 
regarded as slight evidence that the monarch structure in 
roots of Ophioglossum and rootlet-bases of Botrychium is 
a case of reduction. If monarch structure were primitive 
for the group, and retained in some species, one would expect 
to find it in the first root of the seedling in others. 
If the monarch structure in Ophioglossum vulgatum is to 
be regarded as reduced from the diarch type, there should 
be some physiological peculiarity with which this reduction 
is connected. 
The horizontal position of the roots is no doubt connected 
with the production of adventitious buds, the roots keeping 
at a convenient distance below the surface of the soil. 
Monarch structure, of the type and orientation found in 
Ophioglossum vulgatum , may have arisen from the diarch 
form as a means of favouring the development of numerous 
adventitious buds. Thus, to suppose a phylogenetic series, 
the diarch root would probably produce an adventitious bud 
about opposite one of the protoxylems. If the two phloem- 
groups now become approximated at this side of the stele 
(which we may call the upper), and abortive towards the 
other side, the development of the bud will be favoured, 
because most of the phloem will convey nourishment to the 
adventitious bud, and there will be only a little phloem 
towards the lower side of the stele to carry nourishment 
direct to the root-apex. Further modification in the same 
direction would result in the fusion of the two phloems on the 
upper side of the stele, where the adventitious bud is. This 
would lead to the abortion of the protoxylem on that side, 
1 Jeffrey, The Gametophyte of Botrychium virginianum ; Transactions of the 
Canadian Institute, vol. v, 1896-7, p. 283. Specimens obtained from him showed 
diarch structure in the first root. 
