Exochite 
Expansion 
ing of MesisteM ‘‘thickening ring” 
and PERISTEM, young cortex ; it is 
the tissue of protomeristem which 
is not young pith. 
Ex’ochite (fw, outside, yids, a tunio), 
the outermost membrane of the egg 
in Fucaceae (Farmer) ; Exocor’tex, 
(cortex, bark), a special triple layer 
in the roots of saprophytic Orchids ; 
Exoderm’is (dépua, skin), the outer- 
most cortical layer of the adult 
root, answering to *the hypoderma 
of the stem. 
Excoe’mum (é£, out, oludw, I issue), 
a fringe or tuft of hair at the base 
ot the glumes in some grasses 
(Richard); exocatad’romous (+ 
CATADROMOUS), when Ferns in their 
nervation have their stronger 
pinnules anadromous, and their 
weaker catadromous (Prantl); 
Exog’amy (yduos, marriage), the 
tendency of closely allied gametes to 
avoid pairing ; exog’enous exog’enus 
(yevvdw, I bring forth), (1) growing 
as the wood of Dicotyledons ; (2) 
arising from superficial tissue ; 
Ex’ogens, Hxog’enae, plants which 
increase in growth by the addition of 
wood on the outside beneath the 
constantly widening bark ; Exog’y- 
nous, exog’ynus (yyy, woman), where 
the style is exserted beyond the 
flower ; Exoisog’amy (+Isocamy), 
when a gamete will pair only 
with a similar gamete of another 
brood (Hartog) ; exonas’tic (vacros, 
pressed close), in anatropous or 
campylotropous ovules when the 
curvature is horizontal towards 
the median nerve of the side of 
the upper face of the carpel 
(Van Tieghem) ; ¢f. ENDONASTIO ; 
Exoneuro’sis (veipov, a nerve), the 
separation of veins in appendicular 
organs, and their reappearance as 
teeth, spines, or bristles, as in the 
Barberry (Clos) ; Exoperid‘ium (+ 
Peripium), the outer layer of the 
peridium of such Fungi as Lycoper- 
don, which peels or flakes off on 
maturity ; exophyll’ous -us (guddov, 
a leaf), not having a foliaceous 
96 
sheath, with naked cotyledons : 
exop’tile, exop'tilis (mrti\ov, a 
wing) EXOPHYLLOUS, said of 
an embryo whose plumule is naked 
upon, or between cotyledons and 
not rolled up in one (Lindley); 
Exorhi’zae (pita, a root), = Exoarns; 
exorhi’zal, exorhiza’lis, the radicle 
not sheathed, so the primary root 
in germination has no covering to 
pierce; Exos’mose, Hxosmo'sis(dwapds, 
a thrusting), the passage through a 
membrane outwards from a thin to 
a dense fluid ; Exosclero’tes («xnpos, 
hard), sclerotia which are externa] 
to the surface of Agarics; Ex’- 
ospore, Hxospor’ium (amopd, seed), 
(1) the outer covering of the spore ; 
(2) a thick coat developed from the 
otis round the odspore in 
eronosporeae ; exos’porous, hav- 
ing scattered spores, as Fungi; Ex’- 
ostome, Hxost'oma (sréua, amouth), 
the foramen of the outer coat of the 
ovule; Exosto’sis (éc7éov, bone), 
(1) the nodules on roots of Legumi- 
nosae ; (2) the hard turgescence of 
sound wood, showing as prominent 
knots; Exosty’lus ¢ (+ Sry.us), 
Mirbel’s word for fruit as in 
Labiatae, four seemingly naked nut- 
lets ; Exothe’cium (47x, a case), (1) 
the outer case of the anther 
(Henslow, Lindley) ; (2) Purkinje’s 
term for the extine or outer 
layer of pollen-grains. 
exoter’ic (€fwrepixos, external), aris- 
ing from outside the organism, the 
opposite of ESOTERIC, 
exot‘ic (éfwrixos, foreign), not native, 
introduced from abroad ; Exot‘ics 
are those plants which are not in- 
digenous. 
exotroph’ic (¢fw, out of ,rpodh, nourish- 
ment), employed by Wiesner where 
an organ or lateral shoot, as op- 
posed to the mother-shoot, is most 
strongly developed; Exot’rophy, 
development of lateral shoots 
instead of the main axis, 
expand’ed, expan’sus (Lat. spread 
out), diffuse ; Expan’sion, the con- 
dition of a flower in full perfection ; 
