MULTIJTJGATE TYPES. 



171 



while normal (16 + 26) and (42 + 68) have been already noticed in 

 Eelianthus, one capitulum was recorded as presenting the type 

 (26 + 42).* 





\//-T:t>(:^ 





Fig. 63. — Geometrical construction for a system (6 + 7) with complementry system 

 (1 + 13) : JEchinopsis multiplex, giving a 13-spired shoot with genetic spiral 

 winding on apex. 



As these anomalous capitula are rare in Helianthiis, but the rule 

 in JDipsacus, the section of the expanding series should prove of 



* Such numbers being derived from observation of the external characters of 

 the mature capitula, do not necessarily give the construction system, since if the 

 facets observed subtend a smaller angle than the original primordia at their 

 insertions, a higher series of curves wiU be apparent as the contact lines judged 

 by the eye. 



