PLA 



PLA 



large spongy organ vliich rccoivcs 

 tlip blood of tho motlK^r, ami supplies, 

 hy tliP uinbiiical artery, tho fcntus. 



In botany, eeliiilar tissue devcloppd 

 within a carpel, to wliieii the ovules 

 are attaehed sometimes by an umbil- 

 ical cord. 



PLAITED, PLICATE. In bota- 

 ny, folded like a fan. 



PL.\(;rE. A violent, contagious, 

 and typhoid disease. 



PLANARIA. A genus of flat en- 

 tozoic animals, which do not, how- 

 ever, inhabit the bodies of other an- 

 imals. 



PLANE. A flat surface. 



PLANE TABLE. A square board, 

 furnished with a compass, and with 

 lines drawn on its upper side, used 

 in taking angles and in measuring 

 land. 



PLANE-TREE. The button- 

 wood. 



PLANER-TREE. Planera vlmi- 

 folia {aquatica). A tree of twenty- 

 three to thrity feet height, growing 

 in swampy places, in the South and 

 Southwest, and resembling the elm. 

 The wood is hard and strong, but 

 there is only a small amount of it. 



PLANIPENNATES. Neuropte- 

 rous insects with flat wings, the low- 

 er pair of which equal the upper. 



PLANKS. Boards of nine inches 

 or more in width, and one to two 

 inches thick ; they are sold by the 

 square foot. 



PLANO-CONCAVE. A thin disk, 

 having one surface flat and the other 

 curved inward {concave). 



PLANT. A complex organiza- 

 tion, produced from seeds or sporules. 

 The most general characters are the 

 presence of cellular tissue, and the 

 power of decomposing carbonic acid 

 in light ; but the latter function does 

 not belong to fungi. 



PLANT CASES, WARD'S. Tight 

 glazed boxes, at the bottom of which 

 a layer, six inches deep, of garden 

 mould, in a moist state, is placed ; 

 and in which plants being set, are 

 said to grow without farther trouble 

 if the case be well closed. 



PLANTAIN. The genus Plantar 

 go ; for the most part perennial weeds 

 530 



in meadows ; they are nutritious, but 

 grow too small for hay. The P. ma- 

 jor is called white man's footsteps ; 

 it is commonly recommended as an 

 application to wounds, being mucila- 

 ginous. 



PLANTATION, PLA NTl NG. 

 " Planting is the operation of placing 

 in the soil the roots of a plant which 

 has been previously removed ; and 

 the preservation of the roots is the 

 first thing to be attended to. It 

 should be kept in mind that the span- 

 ffjole.i, or delicate extremities of the 

 fibres, are the parts by which the 

 chief supply of food from the earth is 

 absorbed by the plant. Their tissue 

 being tender and almost naked, they 

 are very susceptible of injuries from 

 mechanical action ; and being adapt- 

 ed for performing their functions in 

 a humid medium, they readily suffer 

 from being kept for any length of 

 time exposed to free air and drought. 

 In taking up the plants, therefore, 

 the roots should be loosened in such 

 a manner as to receive the least pos- 

 sible violence in the operation. Plants 

 in pots can be shifted from one place 

 to another without exhibiting symp- 

 toms of deranged functions ; and if it 

 were possible to preserve the spon- 

 gioles of a large tree as entire as 

 those of a plant in a pot, the same 

 successful result would follow ; but 

 as it is next to impossible to do this, 

 we can only attempt to preserve 

 them as far as circumstances will 

 permit. If the tree be large, a trench 

 should be opened beyond tlie extrem- 

 ities of the roots, of sufficient width 

 and depth to allow the process of un- 

 dermining to be freely carried on. 

 The roots should be gradually set at 

 liberty by a round-pronged fork, the 

 prongs tapering so as to be easily in- 

 serted, yet not by any means so sharp 

 as to prick the roots. As the fork is 

 being used, the soil from among the 

 roots will fall into the open trench ; 

 hut as it accumulates there it must 

 be cleared away, and, at the same 

 time, the portion of roots set at liber- 

 ty will reipiire to be slightly tied to- 

 gether with pieces of matting, and, 

 if necessary, supported by temporary 



