MERISTIC PHENOMENA 51 



are in every respect Begonia phyllomaniaca, so far as the char- 

 acters of stems and leaves are concerned. These plants, of 

 which we have sixteen, were made by fertilising B. heracleifolia 

 with B. polyantha. They are all beginning to break out in 

 "phyllomania." As yet they have not flowered, but as they 

 agree in all details with phyllomaniaca there can be little doubt 

 that the original plant bearing that name was a hybrid similarly 

 produced. The production of "phyllomania" on a hybrid 

 Begonia has also been previously recorded by Duchartre. 17 

 In this case the cross was made between B. incarnata and lucida. 

 The synonymy of the last species is unfortunately obscure, and 

 I have not succeeded in repeating the experiment. 



FIG. 5. Piece of petiole of Begonia phyllomaniaca. The proximal end is to the 



right of the figure. 



From these facts it seems practically certain that the condition 

 is one which is due to the meeting of complementary factors. 

 At first sight we may incline to think that the phyllomania is in 

 some way due to the sterility. This however cannot be seriously 

 maintained; for not only is sterility in plants not usually associ- 

 ated with such manifestations, but we know a Begonia called 

 "Wilhelma" which is exactly phyllomaniaca and equally sterile, 

 though it has no trace of phyllomania. This plant arose in the 

 nurseries of MM. P. Bruant of Poitiers, and has generally been 

 described as a seedling of phyllomaniaca, but from the total 

 sterility of that form this account of its origin must be set aside. 



The phenomenon in this case can hardly be regarded as 



17 Bull. Soc. Bot. de France, xxxiv, 1887, p. 182. 



