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 

 (X^a, that which is poured), the 

 thick fluid albuminous substance 

 of the cell-body (Strasburger) ; 

 Plasmoder'ma (Sty/ua, skin) = ECTO- 

 PLASM ; Plasmodia'tion, the assumed 

 softening of the outline of a spore 

 on its germinating (A. S. Wilson) ; 

 Plasmodie'resis (Stafpeerts, 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 (ff-rrep/aa, a seed), applied 

 to certain fossil fruits, flattened in 

 transverse section ; cf. RADIO- 

 SPERMS (F. W. Oliver). 



Plate-rings, the external concentric 

 strands of vascular tissue in Medul- 

 losa (Jeffrey). 



Pleog'eny (yevos, race), mutability of 

 function ; adj. pleogenet'ic ; Pleo- 

 mor'pnism (nop^y, shape), muta- 

 bility of shape ; adj. pleomor'phics ; 

 pleophylet'ic (ir\eot>, more, tpv\T), a 

 tribe), descended from numerous 

 lines, polyphyletic ; pleoph'agous 

 (<t>dyos, a glutton), not restricted 

 to one host ; feeding on various 

 species ; Pleoph'agism is the con- 

 dition ; pleotroph'ic (rpo^, food), 

 feeding on various Substances, not 

 restricted to one (Jones). v 



pleuroblas'tic, (2) employed by Cela- 

 kovsky" to denote the early stages 

 of the monocotyledonous embryo ; 



Cf. ACROBLASTIC. 



pleurococca'ceous, pleurococ'coid 

 (etSos, resemblance), like the genus 

 Pleurococcus, or its allies. 



Pleu'ston (Tr\v<rTiK6s, ready for sail- 

 ing), plants which float by reason 

 of their relative lightness (Forel), 

 '--flora, practically PHYTOPLANK- 

 TON. 



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 ( + GAMETE), consisting 

 of many gametes or sexual units. 



plurlVorous (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 ; pneumatic Tis'sue, 

 open tissue containing much air 

 (Kearney). 



Pno'ium (TTVO^, a blast), a succession 

 of plants on teolian (drifting) soils, 

 such as blown sand (Clements). 



Pocil'lus, pi. 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). 



poi 1 ilodynain'ic (Troi/cfXos, various, 

 StWjtus, power), in hybrids when 

 the character of one parent is 

 practically absent; poikilother'mic 

 (Qep/jM), 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) ; poopb/ilus (tfuXe'w, 

 love), meadow-loving ; Po'ophyte 

 (<f>vTov, a plant), meadow plants 

 (Clements). 



Point'er Cell, an English equivalent 

 for DEUTER ZELL. 



Polemonie'tum, a plant association 

 of Polemonium (Clements). 



Pollen-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- 



348 



