COHESION AND SUPPRESSION. 



241 



comparison with other species of the genus we find 

 the original condition to have been a dichasial cyme of 

 three flowers, of which in some the terminal flower 

 has disappeared, the two lateral ones being still free, in 

 others, as L. cdpigena and L. Xylosteum, the third step 

 has been taken in reduction, viz., union of the two 

 lateral flowers. 



Now, it is of great interest to find, as described by 

 Velenovsky, that in L. Alberti (in which species flowers 

 with both perfectly free and those with fused ovaries 

 normally occur) abnormal flowers sometimes are found 

 in which the upper portion of each flower, viz. the 

 corolla and andrcecium, become as intimately fused as 

 do the ovaries ; such a synanthic flower then possess- 

 ing a 9-merous corolla and androecium (PI. LI, 

 figs. 7 and 8). 



The phenomenon of synanthy is a progressive one. 



Negative Dedoublement. 



The term "negative dedoublement" was applied by 

 Celakovsky to all those cases in which at some stage 

 of the development the primordium is double, or 

 shows a tendency towards doubling, but in which the 

 phylogenetic tendency is towards fusion. Suppression 

 represents a further evolutionary step in the reductive 

 direction. 



General. — Those cases are included here in which 

 the flower as a whole is affected by the reduction- 

 process, fusion or suppression or both occurring in 

 all the whorls. 



Examples of reduction to pentamery will first be 

 mentioned. 



In Lilt am candid urn. it was noticed that on several 

 plants the terminal flower of the inflorescence was 

 partially 5-merous. The two perianth-whorls, each 

 normally 3-merous, had rearranged their parts so as 

 to make a single 5-merous whorl ; of these five leaves, 

 two are completely external and devoid of dorsal 



VOL. II. 16 



