875 



beginning of an inter-fascicular cambium which, developing further, would 

 have closed the peripheral bundles into a circle. 



From the many observations already made on leaf cuttings, the assump- 

 tion is justifiable that the processes described above for begonia may occur 

 also in many other leaf cuttings. The foliage shoots develop from more or 

 less superficial cells ; the root primordia are produced from the cells border- 

 ing the cambial zone and either break through the old tissue of the cuttings 

 or arise from the cicatrization tissue of the wound. Variations in the 

 different genera are usually unimportant and differences of opinion among 





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Fis. 208. Leaf cutting: from a hybrid form of Begonia Rex. 



the various authors are often explained by the fact that individuals of the 

 same plant species under different conditions and of different age do not 

 always show exactly the same processes. Beinling's^ investigations, for 

 example, prove that the genus Peperomia does not form any callus but 

 covers the cut surface with wound cork. He also found buds produced 

 from the ground parenchyma of the petiole, or the blade, but not from the 

 epidermis and always independent of the vascular bundle. On the other 



1 Beinling-, E., Untersuchimgen liber die Entstehung- der adventiven Wurzeln 

 und Laubknospen an Blattstecklingen von I'eperomia. Inauguraldissertation. 

 Breslau 1878, p. 23. 



