Nutrients 



115 



PlG. 36. Removal of blocks containing undisturbed cambium 

 from large trees. The surface bark is shaved off, four deep in- 

 cisions made, well into the sap wood, and the block removed with a 

 chisel and transferred to a sterile Petri dish in which it can be 

 carried to the laboratory. 



Fig. 37. In the laboratory the block is broken open carefully at 

 the cambium level and fragments of tissue removed for cultivation 

 on nutrient agar. 



