THE PRINCIPLE OF ADHESION. 83 



80, however, in Aristolochia, according to Van Tiegliem, 

 though often described as such.* 



To summarize the above remarks, it seems clear that all 

 adhesions between the two whorls of the perianth, to be 

 found mostly in the Calyciflorce, is an accidental occurrence 

 due to the hypertrophied condition of the axis in forming a 

 receptacular tube ; so that the term " perigynous " is more 

 strictly applicable than," episepalous." 



Adhesions betv^een the filaments and corolla, or calyx if 

 the former be wanting as in Bapline, is an adaptation to insect 

 fertilisation ; whereby a more rigid position is acquired for 

 the stamens, coupled with a gain of leverage, etc. 



Lastly, adhesions between the stamens and pistil only 

 occur where there is a receptacular tube, or " disk," as in 

 Nymphcea ; and the fusion of filaments with the style, or 

 between anthers and stigmas, is brought about by the very 

 close proximity of the organs when in an early and undif- 

 ferentiated state. 



• Dnchartre, EUm. de Bot., p. 648 ; Henfrey, I.e., p. 125 j Benth. and 

 Hooker, Gen. PL, vol. iii., pt. 1, p. 123 ; Yan Tieghem, TraiU de Bot, i., 

 p. 422. 



Van .Tieghem's description and fignre (Fig. 21) is as follows : — 

 " The styles and stigmas are abortive, iind the six carpels 

 are reduced to their ovaries. It is, then, the thickened 

 connectives of the anthers, coherent laterally into a tube 

 and covered above with stigmatic papillae, which now play 

 the part of stigmas and of the style." 



To judge from Payer's fignres {Organoginie, pi. 91 and 

 pi. 109), the stigmas appear to rise from the inner side of the 

 verv short filwments, and might be interpreted as truly car- 

 pellary stigmas, bnt fused to the former. A further investi- 

 gation of the distribution of the fibro-vasoular cords should Fig. ai.— Aris- 

 be made. Moreover, Asarum does not appear to have any. yan rleghem')' 

 thing so abnormal. 



