EXCRESCENCES. 221 



Far more dangerous, however, are the root-galls 

 due to such insects, because here the damage is 

 not so local : the water-supplies are cut off, and 

 injurious consequences result from the absorption 

 of the products of decomposition in the soil. 



Notes to Chapter XXIII. 



In addition to the literature on galls quoted in the Notes to 

 Chapter XIV., the reader should consult Dale "On certain 

 Outgrowths (Intumescences) on the green parts of Hibiscus" 

 Proc. Cmnbr. Phil. Sac, Vol. X., 1899, p. 192, and Br/f. Ass. 

 Rep.., Bradford, 1900. 



The detailed study of the anatomy and histology of Galls 

 has been recently undertaken by Kiister, '"'' Beitrage zur 

 Kennttiiss der Gallenanato)iiie^'' Flora, B. 87, 1900, p. 117, 

 where the principal references will be found. 



On the root-galls due to Nematodes see Atkinson in Science 

 Contributions fro7n the Agric. Expt. Station., Alabama., Vol. I., 

 p. I, 1889; Percival, "An Eel-worm disease of Hops" in 

 Natural Science, Vol. VI., 1895, p. 187 ; and MoUiard in 

 Revue generate de Botatiique, Apl., 1900, p. 157, where the 

 histology is dealt with. 



The nodules of the roots of Leguminosae are not part of 

 the subject of this work : the literature is collected in Science 

 Progress, 1895, Vol. III., p. 252, and Dawson, Phil. Trans., 

 1900. 



