DIFFERENT ORIGIN OF EQUIVALENT MEMBERS. 
known are those which are formed abundantly in the indentations of the leaves of 
Bryophyllum calycinum; according to Hofmeister ^ they arise before the complete un- 
folding of the leaf as small masses of primitive parenchyma in the deepest parts of the 
incisions of the leaf. In the aquatic Utricularia 'vulgaris weak shoots arise, according 
to Pringsheim 2, mostly in the neighbourhood of the axils of the divisions of the leaf ; in 
both cases these shoots are of exogenous origin. Nothing is known of the develop- 
ment of the buds produced on the leaves 
of Atherurus ternatus or Hyacinthus Pouzohit 
(Doll, Flora von Baden, p. 348). 
(b) Adventitious shoots springing from 
Roots are always endogenous; they arise, 
according to Hofmeister, in the neighbour- 
hood of the fibro-vascular bundles or in the 
cambium, as in Ophioglossum, Epipactis mi- 
crophylla, L'lnar'ia 'vulgaris, Cirsium ar'vense, 
the aspen, and apple. 
(c) Ad'veniitious Buds arise moreover 
in an endogenous manner under peculiar 
circumstances from older detached leaves 
or pieces of stem and root, especially when 
kept damp and in darkness. On this de- 
pends the propagation of many plants in 
gardens, as of Begonias from leaves, Marat- 
tias from their thick stipules, &c. Adven- 
titious buds also sometimes appear in con- 
siderable quantity in old stems of woody 
plants ; this occurs on the callus formed 
between the bark and the wood, when 
the stem is cut off above the root. The 
branchlets which break out in old stems 
of Dicotyledons and Monocotyledons are, 
however, often not true adventitious shoots, 
but old dormant 'eyes' which have been 
left behind, having been formed at an 
earlier period as normal exogenous axillary 
buds, when the stem itself was still in the 
bud-condition ; they had become enveloped 
by the bark as the stem increased in thick- 
ness, and carried on a feeble existence, 
until placed in a condition for active 
growth by a favourable accident, as the 
removal of the stem above them (Hartig). 
(d) In the genus Isoetes the leaf-bearing shoot arises exclusively from the fertilised 
germ-cell or embryo, and forms neither normal lateral buds out of the stem nor any 
from the leaves or roots, nor any kind of adventitious buds. 
(e) The Normal Formation of Lateral Shoots from the primary meristem of the growing 
point of the primary axis is endogenous in Equisetaceae ^. With the exception of the 
primary axis which is developed out of the embryo, all the lateral shoots are here of 
^ Hofmeister, Allgemeine Morphologie, p. 423. 
^ Pringsheim, Zur Morphologie der Utricularien ; in Monatsb. der k. Akad. der Wissen. Berlin 
1869. 
^ [Some doubt is, however, now thiov^'n on this exception ; see Book II, Equisetaceoe.] 
Fig. 128. — Equisetiim arve}ise; longitudinal section through 
an underground bud in March ; ss the apical cell of the stem ; 
b — 9 b its leaves ; Ä' K' two endogenous lateral buds exposed by 
the section. The youngest rudiments of buds are to be found, 
however, at b", amd they have probably begun to be formed 
even at a greater height {X 50). 
