PEAR PEDICULUS. 



417 



wood is carefully preserved over every part 'of the 

 tree, and young branches are ever rising from the 

 lower parts of the tree, to succeed those which have 

 become worn out above. 



These trees bear their fruit only on the moderate- 

 sized shoots of the former year ; and this is one 

 reason why so mu^h skill is required in their manage- 

 ment. Standards in the open ground need no pruning, 

 because the head takes its natural rotund form, and 

 the vigour being distributed into so many channels, it 

 is never redundant in any one place. Standard peach 

 trees are, however, but seldom seen in our gardens, 

 being seldom fruitful unless they stand in very 

 sheltered situations. 



PEAR is the Pyrus xativa of De Candolle. A 

 hightlv-improved garden and orchard fruit-tree. The 

 pear is found wild in England, and probably over all 

 the continent of Europe. In its wild state the fruit 

 is small, hard, and austere ; but, since its domestica- 

 tion, new varieties of the greatest excellence have 

 been obtained, vying in flavour even with some of our 

 best peaches, and, in one respect, superior to them, 

 in keeping good for several months after being taken 

 from the tree. 



The different varieties are propagated by grafting 

 on stocks raised from the seeds of any of the common 

 sorts, more especially those of vigorous and upright 

 growth. Sometimes quince-stocks are used for parti- 

 cular sorts, especially if the trees are required to be 

 dwarfs. 



In gardens the pear is trained on walls, or as 

 espaliers, or trained in the low bush-form on the 

 borders of compartments. Such as are planted as 

 riders on walls, or high standards in orchards, always 

 come into bearing sooner than dwarfs planted in the 

 same places, because the former grow with less 

 vigour. 



Crops of pears are frequently lost by reason of 

 their early flowering. Night frosts often occur when 

 the *rees are in blossom, and the protruding style of 

 the flower, being remarkably tender, is sure to suffer ; 

 and, notwithstanding the hardy character of the tree, 

 the flowers are as easily killed as those of the peach, 

 and require covering quite as much. 



The old sorts of the French pears, such as the 

 colmar, cressanne, St. Germain, c., do best on east 

 or west walls ; but the new sorts lately introduced 

 from France and Belgium are found to do well as 

 standards. 



Young trees require a longer period of time to 

 come into bearing than most other sorts of fruit-trees. 

 This is discreditable to the gardening world, as 

 assuredly there are practical means by which this 

 defect of the pear-tree might be easily remedied. 



PEDALINE^E. A natural order, containing only 

 one genus, of which there is only a solitary species 

 yet discovered. The plant is a herbaceous annual, 

 found in India ; its leaves, when steeped in water, 

 render it viscid, in which state it is recommended to 

 be drunk by patients suffering under dysuria. The 

 Pedalium tnurcx was formerly placed among the 

 Iiignoniacc(E, but separated on account of the small 

 number of seeds in each cell of the fruit. 



PEDICULARIS (Linnaeus). A numerous genus 

 of herbaceous perennials, chiefly European. They 

 are placed by Linnaeus in his fourteenth class, and in 

 the natural system among the Scrophularina;. In our 

 hardy collections they thrive best in sandy heath- 

 mould, and] the choicer sorts should be potted and 



NAT. HIST. VOL. III. 



kept in frames during winter. They are propagated 

 by seeds. 



PEDICULUS (Linnaeus). A genus (or more 

 strictly, Pediculidea, Leach, a sub-order) of apterous 

 insects, belonging to the order Anophtra, Leach, of 

 minute size and parasitic habits, having only six legs, 

 and the abdomen destitute of articulate movable appen- 

 dages. The mouth is minute, tubular, and placed at the 

 anterior extremity of the head on the under side, in 

 form of a small rostrum, and enclosing an instrument 

 for suction ; the tarsi are composed of a single joint 

 nearly as long as the tibia, and terminated by a single 

 claw of considerable size, folding back upon the in- 

 side of the tibia, performing the office of a hook. In 

 several of these particulars we find a difference of 

 character between the suctorial Pediculi and those 

 species of Anoplurous insects which are attached to 

 birds composing the sub-order Nirnridea (Ricinus, 

 De Geer), and which have the mouth mandibulated, 

 the tarsi articulated, and terminated by two claws of 

 equal size. All these insects were, however, united 

 by Linnaeus in the genus Pediculus, and by Leach 

 and Latreille in an order which the former named 

 Anoplura, and the latter Parasita. Some recent 

 German authors have, however, considered these two 

 groups as belonging to different orders, placing the 

 Pediculidea amongst the haustellated insects (Hcmi- 

 plcra cpizoica, Nitzch), and the Nirmidea amongst 

 the mandibulata (Orthoptera cpizoica, c.). We 

 prefer, however, retaining these insects in a single 

 order (Anoplura), on account of their general simi- 

 larity in structure, as well as in their parasitic habits; 

 arid, therefore, having already noticed the mandi- 

 bulated species in the article NIRMUS, and detailed 

 in the article LODSE the natural history of the haus- 

 tellated species, we shall here confine ourselves 

 to a notice of the genera of which the family is 

 composed. 



</, the common louse ; b, magnified; c, one of the legs magni- 

 fied; d, eggs; K, ditto magnified. 



Genus 1. Pediculus, Linnaeus. Thorax composed 

 of three distinct segments as broad as the abdomen, 

 the legs terminated by a ringer and thumb. The 

 common louse (Pediculus humauus}, and head-louse 

 (P. ccrricafis), belong to this genus. The former is 

 comparatively rare. The eggs of these insects are 

 called nits, and are attached to the hairs of the body 

 or head. They are provided at one end with a cap 

 which slips off with ease when the young first bursts 

 forth. The males of these two species have the ab- 

 domen terminated by a small conical scaly organ. 

 . Genus 2. Phthims, Leach. Body short, rounded, 

 thorax very short and indistinct, the four hind legs 

 very thick. Pediculus pubis. 



Genus '3. HcBmahrpintis, Leach. Thorax narrow, 

 distinct; abdomen very broad. The type is the 

 DD 



