^48 PRINCIPLES OF V E^G E X A,T I O.N. . ^ 



A Pear, befides the fkm, whi^h is a produdion of the fkin_pf 

 the bark, confifts of a double parenchyma or puW-ifap.'iBd air-vcfleU, 

 calculary and acetary. ;.',,, -^ -. v- ' - 



The outer parenchyma is the fame fubftance cbntifiued from the bark, 

 only its bladders are larger and more fucculent. • ' 



It is every where interfperfed with fmall globules or grains, and the 

 badders refpe<5l thefe grains as a kind of, centres, every grain being the 

 centre of a number of bladders. Th^ fap and air-veflels in this pulp 

 are extremely imall. ..... , : ., ,«, 



Next the core is the inner pulp or parenchyma, whtch confifts of blad- 

 ders of the fame kind with the outer, only larger "and more oblong;, cor* 

 refponding to thofe of the pulp, from/which it leems to be derived. This 

 inner pulp is much fourer than the other, and has' none of the fmall 

 grains interfperfed through it, and hence it has got the name oi hcetary. 



Between the acetary and outer pulp the globules or grains begin to 

 grow larger, and gradually unite into a hard ftony body, efpecially tC|7 

 wards the corculum, or ftool of the fruit; and from this circurnft^^ce it 

 has been called the ftf/f«/tfry. 



Thefe grains are not derived from any of the organical parts of th^ 

 tree, but feem rather to be a kind of' concretions precipitated from the 

 fap, fimilar to the precipitations from wine, urine, and other liquors. 



The core is a roundilh cavity in the centre of the pear, lined with a 

 hard woody membrane, in which the feed is inclofed. At the bottom of 

 the core there is a fmall dudt or canal, which runs up to the top of the 

 pear; this canal allows the air to get into ^he core for, the purpofe of 

 drying and ripening the feeds. 



In a Lemon, the parenchyma appears in three different forms. Thq; 

 parenchyma of the rind is of a coarfe texture, compofed of, thick- fibrtsj 

 woven into large bladders. Thdfe heareft the furface cohtain the effen- 

 tial oil of the fruit, which burfts into a flame when the fkin i^ fqueezed 

 over a tandle. From this outmoft parenchyma nine or ten infertions. or 

 lamelljE are produced, which run between as many portions oiT the 

 pulp, and unite into one body in the centre of the fruit, which cor- 

 refponds to the pith in trunk or roots. At the bottom and top of the. 

 lemon, this pith evidently joins with the rind, without the intervention of 

 any lamella. This circumftance Ihews that the pith and bark are ac- 

 tually conntdled in the trunk arid roots 6i plants^ "though it i> difficult to 

 demonftrate the connexion, on account of the clofenefs of their texture, 

 ^hd the minutenefs of their fibres. Many vcflels arc difpetled through 



