Planation 



pluriohromosomal 



Plana'tion, employed by Clements to 

 denote stream-erosion. 



pl^ie'tous, plane'tus {nXavjjTos, wan- 

 dering), applied by I. B. Balfour to 

 a migratory species. 



Flaak-bntt'resses, the flat roots given 

 off from the base of certain trees, 

 as Bombax Linn. 



Plank'tont, a constituent of plankton. 



Planom'enon, wandering plankton ; 

 Plaa'ont, a wandering organism. 



Pla'no-piast'id, a flagellate cell; cf. 



APLAIfO-PLASTID. 



Plant-sociorogy, cf. Phytosociology. 



Plasmog'amy {ydfios, marriage), the 

 fusion of cytoplasm, not of nuclei 

 (Minchin) ; Plasmogen'esis (yeVeat?, 

 origin), the origin of protoplasm 

 (Herrera) ; plasmomet'ric {fj-hpov, 

 a measure), measurement of the 

 osmotic pressure of individual cells 

 (Hopler); Plasmone'ma {^'rjfMi, a 

 thread), the conducting threads of 

 protoplasm, communicating with 

 plastids (Janet) ; Plasmop'tyse 

 {iTTvais, spitting), mycorrhiza in- 

 fection of Asclepiads and Apocyna- 

 ceae in the exodermis of the root 

 (Demeter) ; Plasmor'gan ( + Organ), 

 a rudimentary organ (Janet) ; 

 Plasmot'omy (to/^o?, a cut), cleav- 

 age of a Plasmodium into two or 

 more nucleated parts (Minchin) ; 

 Plast'id Primor'dia, large micro- 

 chondria-like structures which pro- 

 duce leucoplastids (Mottier) ; 

 Plastids, add, (2) granules which 

 take a deeper stain than the cyto- 

 plasmic matrix in which they are 

 imbedded (Collins) ; Plast'idome 

 {Bofios, a house, or chamber), the 

 sum-total of plastid contents in a 

 cell (Wilson). 



Plates, the exterior parts of Peri- 

 dinaceae, enumerated by W'^st, as 

 a'pical '- ; ant'apical ~ ; inter- 

 c'alary -^ ; postcin'gular ~, pre- 

 cin'gular ~, and ventral '^. 



Platyopun'tia, any Opuntia or succu- 

 lent plant with flattened stems 

 (Mac Douglas). 



Play'a (Span.), sea-coast or bedch. 



plectenchym'atons (■jtXcktos, woven). 



hyphae matted in growth ; cf. 



I^ECTENCHYMA, PSEUDOPABEN- 



CHYMA, PSEITDO-PYCNIDIAL : PlCCtO- 



myce'tes, a group of fungi in which 

 the richly septate types are never 

 reached and detached spermatia 

 are unknown, as Erysiphaceao 

 ( G Wynne - Vaughan ) . 



Plei'omere {i^^pos, a part), when 

 mitoses have a higher number of 

 chromosomes, and therefore smaller 

 in size (Delia Valle) ; Plei'on, a 

 cycle of abundant corn-crops with 

 excess of temperature (Arctowski) ; 

 pleiosy'gous {ivyos, a 'yoke). 

 Frost's term for unlinked. 



Pleist'omere ( TrAet aro?, most; iUpos, 

 a part), when the chromatin is 

 divided only by granules (Delia 

 Valle). 



Pleog'amy {ydpios, marriage), having 

 flowers of various degrees of 

 maturity, as Andropleoqamy, 

 Eripleooamy and Gynopleogamy. 



Plesias'my {vX-qaiaaiMOb', an approach), 

 abnormal shortening of the stem, 

 so that the leaves arise from 

 nearly the same point (Fermond). 



Ple'thea {ttXtjOos, a crowd), Janet's 

 term for Merism, of a sporadic 

 swarm with its later transforma- 

 tions, adj. ple'thean; Ple'theo- 

 blas'teas, alternations of plethea 

 and blastea resulting in the forma- 

 tion of piano-spores (Janet). 



pleuran'thons {dvdos, a flower), when 

 in a sympodium the inflorescences 

 are borne on lateral axes, the main 

 axis not ending in an inflorescence, 

 but simply stopping in growth ; 

 Pleurocystid'ia (-KCystidta), the 

 cystidia being lateral (Buller) ; 

 pleurog'enous {yevos, offspring), 

 borne laterally on hyphal cells 

 (A. L. Smith). 



Plo'tOphytes {ttXwtos, floating ; (furrov, 

 a plant), floating plants, their 

 functional stomata on the upper 

 surface of their leaves (Clements). 



plurichromoso'mal, when one chromo- 

 some complex takes one or more 

 chromosomes of the other in the 

 reduction division (Lotsy) ; plur'i- 



468 



