NECROTIC DISEASES. 245 



the drought causes the breakage of the water 

 columns above, and the twigs die back. 



Tropical trees may also become stag-headed 

 owine to the attacks of Loratithus and other 

 parasites, the portions above the point of attach- 

 ment dying back from inanition. 



Cases also occur in the tropics where the stag- 

 head condition is due to the persistent roosting of 

 frugiferous bats " flying foxes " w^hich tear the 

 bark and foliage with their claws, and befoul the 

 twigs generally. 



Notes to Chapter XXVI. 



The principal literature as regards frost is given in the 

 works of Frank, Sorauer, and Hartig already referred to. 

 An excellent summary will be found in Hartig's Diseases of 

 Trees, p. 282, and in Fisher "Forest Protection," Vol. IV. 01 

 Schlich's Manual, p. 423. 



