MISCELLANEOUS: EXPERIMENTAL TERATOSIS 575 



in Brazil. He says it grows frequently in Mexico and Central 

 America and thinks De Candolle may be right in supposing 

 it to be of Guatemalan origin. 



Bateson believes the plant to be a hybrid because it is 

 perfectly sterile, because he has seen phyllomania in sixteen 

 hybrids resembling this plant, which he obtained by crossing 

 Begonia heradeifolia with Begonia polyantha, and because 

 Duchartre reported phyllomania in hybrids which Nodot 

 obtained by crossing Begonia incarnata and Begonia lucida. 

 Bateson thinks the phyllomania cannot be ascribed to the 

 sterility of the plant because he knows another begonia called 

 Wilhelma " which is exactly B. phyllomaniaca and equally sterile, 

 though it has no trace of phyllomania." He says: "We 

 would give much to know the genetic properties of Begonia pliyllo- 

 maniaca." Goebel thinks the plant was probably obtained 

 by crossing B. manicata with B. incarnata. His plant sho\ved 

 a rhythmic production of the phenomena, the shoots appearing 

 only in the winter season, but this, I am inclined to think, 

 was only because his gardner repotted the plant in the autumn 

 rather than in the spring. 



The main facts I have discovered are briefly as follows : 



1. The initial impetus to phyllomania on a given leaf or 

 internode is not determined by the amount of photosynthetic or 

 other material in the organ, nor is the phyllomania a low-growth 

 or winter state of the plant, as believed by Goebel, but is con- 

 ditioned on a definite shock. Whether the phenomenon ap- 

 pears in the summer or in the winter depends on when the shock 

 is administered. The phyllomania may be produced at any 

 time of year. 



2. Following such a shock, however, the number of shoots 

 which develop or remain abortive appears to depend on the food- 

 supply. 



3. Leaves and internodes are susceptible to shock only 

 during a brief period of meristematic growth. When they have 

 passed much beyond this period they are no longer susceptible. 



4. The tissues are most susceptible after they have passed 

 out of their most primitive condition, but are still embryonic. 



