Anatomy of the Ophioglosseae. 389 
the first two tracheides have been differentiated, and in this 
case they are close together (one cell apart). Later stages 
are also given ; the production of the adventitious buds is 
described, and the conclusion arrived at that they are formed 
on true roots, not stolons. 
Russow 1 gives a short description and a diagram of the 
root. He describes the root as monarch, the protophloem as 
being in contact with the endodermis, and as appearing some 
time before the protoxylem, and describes the formation of 
a peripheral arc of xylem, followed by centripetal develop- 
ment of the remainder ; but his description and figure would 
give the impression that the first-formed protoxylem-element 
was practically at one end of the arc, and that the develop- 
ment proceeded regularly towards the other end of the arc. 
He also, curiously enough, states that the xylem occupies the 
upper half of the stele, and the phloem the lower. 
Van Tieghem in his earlier work 2 states that the first 
vessels are formed at a single point in the circumference (thus 
making the xylem monarch), and describes the root-bundle 
as being inserted on the stem with its xylem downwards and 
phloem upwards. Thus he had not at that time discovered 
the rotation afterwards described by him. He goes on to 
show that the root of Ophioglossum corresponds in structure 
to half the root of Botrychmm ; and says that, to refer the 
structure in Ophioglossum to the diarch type of Botrychium , 
it is only necessary to suppose that a dichotomy (producing 
monarch branches such as he here claims for roots of 
Botrychmm 3 ) takes place in the cortex of the stem, and that 
the upper branch is constantly abortive. This would mean 
that he interpreted the xylem as truly monarch, a view which 
he abandoned afterwards; for in the Traite de Botanique 4 
the xylem is described as diarch. It is curious that the 
1 Russow, Vergl. Unters., in Mem. de l’Acad. Imp. des Sciences de St.-Peters- 
bourg, vii. ser., t. xix, No. i, 1872, p. 122, and Taf. xi, Fig 31. 
3 Van Tieghem, Symetrie de structure des plantes, Ann. des Sci. Nat., Bot., 
V. ser., t. xiii, 1870-71, p. 107. 
3 1. c., p. 109. 
* Second edition, 1891, p. 1394. 
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