NUMERICAL 1NCEEA.SE OF PAKTS OF PLANTS. 207 



I. Atavism or Reversion. 



1. Dialysis of normally '* coherent " organs. 



i. Of those coherent by organic nnion. 

 ii. Of those coherent by mechanical union. 



Solution of normally "adherent" organs. 



o 



II. HTPERTEOPHr. 



1. PolyphyUy : 



i. by the increase in number of individual parts, either of some 



or all those of a whorl, 

 ii. by the '^symmetrical increase" of whorls. 

 iii. Restoration to a higher ancestral number. 



2. Pleiotaxy : 



i. By the increase of the number of whorls. 

 ii. By the increase of the number of cycles. 



3. Pleiojyhylly by the production of supernumerary leaflets 



i. Accidental numerical increase. 

 ii. Partial or entire restoration. 



III. Supplemental Developments. 



1. Plication, 



3, Enation, producing appendicular processes. 



IV. [Cause obscure.] 

 Chorisis^ fission^ or bifurcation. 



i. of axes. ii. of axial appendages. 



V. Ateophy. 



Formation of compound foliar organs. 



I. Atavism. — Under this head I would inchide Dialysis and 

 Solution (Veg. Ter. Masters, pp. 69 & 76). For, I assume, on the 

 well-known principles of evolution, that all normally coherent 

 organs were originally free and distinct in their ancestral condi- 

 tions ; so that whenever normally united parts are developed free 

 from each other, such I consider to be due to reverrion in the 

 sense of atavism. 



Of cohesion T would recognize two kinds ; 



i. Organic^ when the parts emerge from tlie axis already 



coherent, as do gamopetalous corollas. 

 ii. Mechanical, when the parts are at first quite free, but 



unite subsequently by their adjacent edges, becoming 

 coherent ; as do the anthers of the Compositce (by muci- 

 lage) and the stigmas of Asclepias, 

 Of examples of £?*Wym maybe mentioned polypetalous Cam- 



