TORUS, DISK, NECTARIES. 



75 



448. Apple. 



Young fruit cut 



transversely. 



447. Chelidonium. 

 Pistil (mag.). 



449. Apple. 

 Fruit cut vertically. 



on the receptacle, between the pistil and the calyx (Clielidoniwn,fig. 447). In every 

 case the andrcecium and corolla, being inserted on this ring and below the pistil, are 

 hypogynous, and the plant thalamifloral if the c 



petals are free, corollifloral if they are coherent. 



In many plants the receptacle dilates into 

 a cup, which represents a calycinal tube, over 

 which the torus is spread, 

 and the stamens and pistils 

 spring from its outer 

 margin (Strawberry, fig. 

 401 ; Apricot, fig. 449). 

 In others it rises upon the 

 carpels, envelops them 

 closely, and forms with 

 them but one body, upon the circumference of which the stamens, petals and calyx 

 are inserted at a higher level than the ovary (Myrtle, fig. 381 ; Saxifrage, fig. 382). 

 This cup, enveloping the carpels and formed by the growth of the receptacle, is the 

 calyx-tube of modern Floras, which it would be better to call a receptacular tube 

 or cup. 



This hypertrophy of the receptacle is particularly striking in orchard fruits. If 

 we halve an unripe pear or apple (fig. 448), we find five carpels, forming five two- 

 ovuled cells, surrounded by a fleshy mass, the so-called caly cine-tube (better called 

 receptacular cup], which has closely enveloped them, and agglutinated them by their 

 lateral faces, but left their inner edges free. A vertical section of a ripe apple (fig. 

 449) exhibits a fibro -vascular bundle, extending from the peduncle, with which it is 

 continuous, to the carpels (E) ; it is the parenchyma of the receptacle, which has here 

 enormously increased in bulk to envelop the ovaries (T) ; at the summit of this 

 mass, that is to say, at the top of the fruit, the remains of the sepals and stamens 

 may be seen carried up by the expansion of the receptacle. 



The receptacular theory of the calycine-tube completely explains the arrange- 

 ment of the carpels of a Rose (fig. 405) . In this, the position of the carpels on the 

 internal wall of a calycine-tube was difficult to admit ; the whorls of the flower being 

 lateral expansions of the axis, it was impossible, in defiance of the law of the 

 evolution of floral whorls, to attribute to the calyx the power of producing carpels. 

 The position of the coloured ring from which the petals and stamens rise is the key 

 to the apparently abnormal position of the carpels ; this ring surmounts the ovoid 

 body enclosing the carpels ; the torus has therefore reached that point before emit- 

 ting laterally the petals and stamens; and since the torus is nothing but the 

 circumference of the receptacle, it is evident that it must be the latter organ which 

 constitutes the hollow body enclosing the carpels. In fact, the receptacle, instead 

 of forming, as in the Strawberry (fig. 401), a hemisphere, has swollen, risen much 

 above its ordinary level, and formed a sort of cup ; thus resembling the finger of a 

 glove turned inside out, the normally outer or convex surface becoming the^inner, or 

 concave, one. Were the convex receptacle of the Strawberry reduced to a thin 



