LAYERING 111 



slit. This is what we call a Y-shaped incision, be- 

 cause the raised tongue forms with the rest of the 

 stem an opening like that between the two branches 

 of the letter Y. Through the half that remains in- 

 tact communication with the mother stem is main- 

 tained and the needed share of crude sap is received, 

 while from the cut and upraised half adventitious 

 roots are put forth because the course of the de- 

 scending sap is arrested there. 



"In order to bring into contact with the damp soil 

 a greater extent of wounded fiber fit for putting forth 

 adventitious roots, it is customary to split the up- 

 raised tongue in two and keep the two parts gaping 

 by interposing a small pebble. This method of dou- 

 ble incision is used for trees that offer the greatest 

 resistance to successful layering. 



"To sum up, all these methods and others derived 

 from them have for their object the fostering of 

 adventitious roots by arresting the course of the 

 descending sap at a certain point beneath the soil. ' ' 



