199 



The , .négative" internodes of the stem may be so explained that 

 this zone may be oblique and may pass over a higher and under a 

 lower number of the ongmal phyllotaxis. This is only a new proof 

 for the thesis, already held by Braun^ that the distinction between 

 node and internode is only valuable in the case of the simple terms 

 of the phyllotaxis séries, but that in the higher terms, as scon as 

 several leaves are inserted on the stem side by side, the distinction 

 looses its significance. 



4. The inflorescence of Primula. Itis a well known phenom- 

 enon in several species of the genus Pnmula, that the inflorescence, 

 instead of forming a single umbel, has tw^o, three or more distinct 

 zones each with numerous flowers. Thèse zones are sometimes 

 called superposed umbels, in other cases they are designed in the 

 literature as whorls. 



A simple investigation was sufficient to show that in thèse in- 

 florescences we hâve without any doubt another case of the same 

 growth whorls as described of Lilium and Ferula. 



A species I examined was Pnmula Bidleyatia Forrest", from the 

 Groningen Botanical Gardens. Just as in the former cases, the 

 numbers of the flowers in the succeeding whorls did not show any 

 corrélation; so in ten inflorescences I counted: 



^ Tannenzapfen, I. c. p. 345. 



' No. 11493 of the Catalogue. 



