polar 



Pollen 



rootlet (Lopriore) ; '-' biloc'ular, 

 applied to Lichen spores which have 

 cells at the opposite apices ; Bod'y, 

 Bod'ies, a portion of the protoplasm 

 of a mother-cell thro\\Ti off as nu- 

 cleated cells from the oospore before 

 fertilisation ; --' Cap, an ill-defined 

 region of kinoplasm, generally larger 

 than a centrosphere, for insertion of 

 spindle-fibres (B. M. Davis) ; -- Cell, 

 = -- Body ; <- Corpus'cle, the 

 central mass in each Aster of a 

 dividing nucleus; -^ Glob'ule, = 

 -- Body ; <- Nu'cleus, a fourth 

 nucleus in each group at the two 

 extremities of the embryo sac, which 

 move towards the middle of the 

 embryo sac and there coalesce to 

 form the secondary nucleus ; '*- 

 Plates, the achromatic spheres at 

 the poles of the spindle in mitosis ; 

 '^ Bays, sometimes applied to the 

 asti-al rays as opposed to the spindle- 

 fibres ; pola'ri- biloe'ular, used of 

 two-celled spores with a thick cen- 

 tral wall traversed by a connecting 

 tube, the lumen of the cell at the 

 extreme end ; Polarity, (1) the con- 

 dition of having distinct poles ; (2) 

 the assumption of a direction point- 

 ing to the poles, as the compass- 

 plant, Silphium laciniatum, Linn. 



Polem'bryony = Polyem bryony. 



Polemonie'tum, a plant association of 

 Polemonium (Clements). 



poleward [dissyl.], towards the poles, 

 in nuclear division. 



Polezostylas {-koXvs, many ; i{w, 

 out ; arvXos, style) = Carcerule. 



Po'lioplasm {TroXths, grey ; rrXdfffia, 

 moulded), Tswett's term for the 

 circulating portion of the cyto- 

 plasm. 



Polit'ropism = Polytropism. 



poli'tus (Lat.), polished. 



pollaoan'thic, preferably pollachan'thic 

 (iro\\axv, often ; &vdos, a flower), 

 afiplicd to plants which flower more 

 than once, as opposed to hapaxan- 

 THic plants ; perennials (Kjellman) ; 

 pollachig'enus (yewdw,! bring forth) 



= P0LYCARPIC. 



Poirard, a tree dwarfed by frequent 



cutting of its boughs a few feet from 

 the ground, and subsequent thick 

 growth of shoots from the place 

 where cut ; poirarding, cutting 

 back to produce a mop-headed 

 growth. 

 Pollen (Lat., fine flour), (1) the ferti- 

 lising dust-like powder produced by 

 the anthers of Phanerogams, more 

 or less globular in shape, sometimes 

 spoken of as "Microspores"; (2) 

 the antherozoids of Mosses (Hooker 

 and Taylor) ; --' Carrier, the retina- 

 culum of Asclepiads, the gland to 

 which the pollen-masses are at- 

 tached, either immediately or by 

 caudicles ; ~ Cells, cavities of the 

 anthers in which pollen is formed ; 

 '-' Cha'mber, (1) a cavity at the 

 apex of some ovules beneath the 

 integuments in which the pollen- 

 grains lie after pollination, as in 

 Cycas ; (2) the extine of the pollen 

 in some Coniferae dilated into two 

 hollow expansions to facilitate dis- 

 persion by wind ; -^ Flow'era, those 

 which afford no nectar to insect 

 visitors, but only pollen ; ^ Grain, 

 Gran'ule, the small bodies which 

 compose the entire mass ; the latter 

 term is also used for the contents of 

 the grain ; ~ Mass, pollen-grains 

 cohering by a waxy texture or fine 

 threads into a single body ; -^ Pre- 

 po'tency, when one kind of pollen is 

 more etfective in fertilisation than 

 another ; -^ Sac, the micro-sporan- 

 gium in Phanerogams ; '^ Spore = 

 '-Gi^mn; '-'Tet'rad, -' Tetrahed'ron, 

 the shape of certain groups consist- 

 ing of four gi'ains cohering in a 

 pyramid, as in Oenothera ; -^ Tube, 

 the tube emitted by a pollen-grain 

 passing down from the stigma to 

 the ovary and ovules ; -' "-' ecto- 

 troplc, the coiirse of the pollen-tube 

 in acrogamy, proceeding along the 

 conducting tissue of the style to 

 the micropyle ; -^ '-- end'otroplc, in 

 basigamy, when their course is 

 towards the base of the ovule 

 (Pirotta and Longo). — The various 

 markings of the pollen-grains in 



294 



