Plasma-membrane 
(SUPPLEMENT) 
Pollen-tubes 
toplasm forming a lining to the 
frustule and enclosing the cell- 
contents (O'Meara); Plas’ma-mem’- 
brane, an equivalent for the German 
‘‘Hautschicht” (Mottier); plas’ma- 
tive, Beccari’s term for period of 
creation of species ; Plas‘mochym 
(xv¥za, that which is poured), the 
thick fluid albuminous substance 
of the cell-body (Strasburger) ; 
Plasmoder’ma (dépua, skin) = Ecro- 
PLASM ; Plasmodia tion, theassumed 
softening of the outline of a spore 
on its germinating (A. S. Wilson) ; 
Plasmodie’resis (d:alpects, division), 
the division of protoplasm, which 
may be (a) akinetic, or (b) karyo- 
kinetic; plas’tic Prod’ucts of kata- 
bolism, those which remain an 
integral part of the organism 
(Parker), 
Plat’ysperms (o7épya, a seed), applied 
to certain fossil fruits, flattened in 
transverse section; cf. Rapio- 
spERMs (F. W. Oliver). 
Plate-rings, the external concentric 
strands of vascular tissue in Medul- 
losa (Jeffrey). 
Pleog’eny (yévos, race), mutability of 
function; adj. pleogenet‘ic ; Pleo- 
mor’phism (yop¢y, shape), muta- 
bility of shape ; adj. pleomor’phics ; 
pleophylet’ic (rdéov, more, PvAy, a 
tribe), descended from numerous 
lines, polyphyletic ; pleoph’agous 
(payos, a glutton), not restricted 
to one host; feeding on various 
Species; Pleoph’agism is the con- 
ition ; pleotroph’ic (rpopy, food), 
feeding on various gubstances, not 
res‘ricted to one (Jones). % 
pleuroblas’tic, (2) employed by Cela- 
kovsky to denote the early stages 
of the monccotyledonous embryo ; 
cf. ACROBLASTIC. 
pleurococca’ceous, pleurococ’coid 
(eldos, resemblance), like the genus 
Pleurococcus, or its allies. 
Pleu’ston (rAevorixds, ready for sail- 
ing), plants which float by reason 
of their relative lightness (Forel), 
~-flora, practically PHYTOPLANK- 
TON, 
348 
Plug, a growth of protoplasm which 
closes the pore-openings in the 
cells of certain Algae, homologous 
with the Stopper of Ballia (H. 
Gibson). 
Plu’mule-bulb, a bulb produced 
directly from germination of the 
seed ; cf. RUNNER-BULB (Blodgett); 
plurigame’tic (+ Gamers), consisting 
of many gametes or sexual units. 
pluriv’ orous (voro, I devour), Dietel’s 
term for those Fungi which in- 
habit indifferently hosts belong- 
ing to widely different orders of 
plants. 
Pneumatho’dium, (1) cf. PNeuma- 
TODE; (2) an AERATING Root, as in 
Taxodium; pneumatiic Tis’sue, 
open tissue containing much air 
(Kearney). 
Pno’tum (voy, w blast), a succession 
of plants on xolian (drifting) soils, 
such as blown sand (Clements). 
Pocil’lus, pl. Pocil’li (pocillum, a 
little cup), the scyphi of Cladonia, 
so termed by Nylander. 
Pock’et, of Lemna, a hollow in the 
leaf, whence a new leaf arises 
(Potter). 
poikilodynam’ic (zocxl\os, various, 
dtvayis, power), in hybrids when 
the character of one parent is 
practically absent; poikilother’mic 
(Gépun, heat), rising and falling in 
response to varying temperature 
(Jones). 
Po‘ium, a plant association in which 
Poa is a predominant genus 
(Ganong) ; (2) a meadow formation 
(Clements); pooph’ilus (giAéw, I 
love), meadow-loving ; Po’ophyte 
(gurov, a plant), meadow plants 
(Clements). 
Point’er Cell, an English equivalent 
for DEUTER ZELL. 
Polemonie'tum, a plant association 
of Polemonium (Clements). 
Pol/len-tubes, ectotrop’ic, the course 
of the pollen-tube in acrogamy, 
proceeding along the conducting 
tissue of the style to the micro- 
pyle; endotrop'ic ~, in basi- 
gamy, when their course is to- 
