C,r,r, REV. G. HENSLOW ON THE VARIATIONS IN 



I. Commencing with a decussate arrangement (D) at the base of the stem : 



1. D into f into f into f 



3 2 



)> >» 8 M 5 



2 



» 7 



3 



4 



5. „ „ f „ f ±i into 



6 4- 3 4- JL 



• 5> 55 ±8 55 J-13 



7. 



8. „ „ (2+l)t „ I 



9. „ „ (2+1) 



7 



5 3 



>J )> 13 " 8 



8 



2 



" 7 



1 1 Commencing with a tricussate arrangement (T) at the base of the stem 



1. T into f 



3 * 



4. „ „ ft into 7 



5. „ „ (2+1) „ | 



2 



1 1 L. Commencing with an alternate arrangement at the base of the stem 



1. J into | into A into | 



2. 



2 



*• * » (2+1) 



2 

 5 



r. 



5- f ,, (2+1) 



Hypothetical Origin of the prevailing series. 



By referring to the diagram (fig. 9) it will be seen that the angular distances included 



by the limiting positions of the second leaves of all generating spirals, commencing at 0, 



decrease according as the spirals belong to the secondary, tertiary, quaternary, Ac. 



wn i; so atoo dors the number of Leaves in a single coil increase correspondingly ; and 



therefore the h, her the series the more nearly does any spiral belonging to it approach 

 h<> v,rtu,llatc > condition, provided the internodes be but slightlv developed. Now, if it 

 >e t uc that these higher seri< , were more abundantly represented amongst -fossil 

 v *Mcs, as M. DecandolleJ remarks, or if, as Mr. Haughtonf says, the verticillat 



I Tv Z V " r * H UmVerSnl1y **"*«***> ■* least by the orders Pilices, Equiset 



.ma Juycn podiac. e, then we o-m T ti,;„i i 



some grounds for at least 



^i:::™:!, 1 : ; ,avo ,,e !° the f ~- <* *>*»£ * ^ k^ .** 2. .. * a 



primary of the present day. But if we attempt to explain how such 



* The symbol ( + 



ndicate* th ,*> f hvo confluent 



p M. 1866 



n 



- vvgemex wun one single leal. 



Par M. C. DeCandolle" (Archives des Sciences Phys. et K«t 



§ Manual of Geology. By R ev . S am . Haughton, p. 245. 



