658 



ORCHIDACEiE. 



ripened, and acquire their ultimate aroma and dark hue. They are 

 then tied together into small bundles. 



In Reunion the drying of the pods is performed since 1857 by 

 dipping them previously in boiling water. 



Description — The fruit when fresh is of the thickness of the little 

 finger, obscurely triquetrous, opening longitudinally by two unequal 

 valves. It is fleshy, firm, smooth, and plump ; when cut transversely 

 it exudes an inodorous slimy juice, abounding in spiculse of oxalate of 

 calcium/ It is one-celled, with a three-sided cavity, from each wall of 

 which projects a two-branched placenta, each branch subdividing into 

 two backward-curling lobes. There are thus in all 12 ridges, which 

 traverse the fruit lengthwise, and bear ^he seeds. Fine hair-like 

 papillae line as a thick fringe the three angles of the cavity, and secrete 

 the odorous matter, which after drying is difiused through the whole 

 pod. The papilla likewise contain drops of oil, which is freely absorhed 

 by the paper in which a pod is wrapped. That the odorous matter is 

 not resident in the fleshy exterior mass we have ascertained by slicing 

 off this portion of a fresh fruit and drying it separately ; the interior 

 alone proved to be frao-rant. 



The vanilla of commerce occurs in the form of fleshy, flexible, 

 stick-like pods, 3 to 8 inches long, and 



compressed cylindrical form, attenuated" and hooked at the stalk end 

 The surface is finely furrowed lengthwise, shining, unctuous, and often 



3 



TU 



to 



3-V of an inch wide, of a 



beset with an efflorescence of minu'te colourless crystals. The pod splits 

 lengthwise into two unequal valves, revealing a multitude of minute, 



hard, black seeds of lenticular form, imbedded in a visciJ 



shining, 



aromatic juice. 



The finest vanilla is the Mexican. Boitrhon Vanilla, which is the 

 more plentiful, is generally shorter and less intense in colour, and com- 

 mands a lower price. 



Microscopic Structure— The inner half of tlie pericarp contains 

 about 20 vascular bundles, arranged in a diffuse ring. The epidermis 

 is formed of a row of tabular thick-walled cells, containing a granular 

 brown substance. The middle layer of the pericarp is composed ot 

 large thin- walled cells, the outer of which are axially extended, wliue 

 those towards the centre have a cubic or spherical form. All contain 

 drops of yellowish fat and brown granular masses, which do not decidedly 

 exhibit the reaction of tannin. The tissue further encloses needles oi 



al 



oxalate of calcium and prisms of vanillin. 



On the walls of the outer cells of the pericarp ^ are deposited spiri 

 fibres, which occur still more conspicuously in the aerial roots and i 

 the parenchyme of the leaves of other orchids. The placentae are coatea 

 with delicate, thin-walled cells. 



^ Chemical Composition— Vanilla owes the fragrance for ^^'^^^^V 

 18 remarkable to Vanillin, which is found in a crystalline state m i' 

 interior or on the surface of the fruit, or dissolved in the viscid on) 



• -^l^^^ J^iS® ^^^^ that of the squill has an 

 irritating effect on the skin, a fact of which 

 the cultivators in Mauritius are well aware. 



a^/i; n * ^,^r^"" ^^ Europe is devoid of 

 such cells. We can fullv nr>,.v..^„...+„ 4.i.;„ 



statement (first made by ^^"^^.^nceA 

 examination of very aromatic P«<?s F - 

 in 1871 at Hillfield House, Kfigate. 

 have even failed in finding t^^o^^ nng), 

 any vanilla of recent importation U^' 



We 

 lis iu 



