439 



square leagues, where there were at least sixty trees. The roots pe- 

 netrate rocky soils with great difficulty, and if ever so slightly injured 

 they decay ; this decay is soon communicated to the trunk, where its 

 progress is very rapid and the tree quickly perishes. Hence it thrives 

 best and is most abundant in wet shifting sands, such as those which 

 extend from Senegal to Cape de Verd, a distance of thirty leagues ; 

 while at Galam, where the soil is a hard stony clay, it occurs much 

 less frequently and is comparatively small. 



Besides a general rottenness or decay arising from injuries received 

 by the root, this tree is occasionally subject to another disease, most 

 probably produced by a fungus somewhat similar to that causing the 

 dry rot, which spreads through the woody portion, and reduces it to 

 the consistence of the pith, without either altering the colour of the 

 wood or changing the disposition of its fibres. The bark also remains 

 uninjured, and there is notliing in the external appearance to indicate 

 the operations of the insidious enemy within. When thus affected the 

 tree is frequently unable to resist the force of the wind ; Adanson met 

 with one in an island near Senegal, the trunk of which had been bro- 

 ken asunder in the middle during a gale. The trunk, at the time he 

 saw it, was inhabited by an immense number of very large Coleop- 

 terous larvae. The disease by which the tree was desti'oyed had most 

 probably made considerable progress before the insects deposited 

 their eggs in the tnmk ; at all events we know this to be the case with 

 willows and other trees, which are seldom if ever attacked when in a 

 souni and healthy state. 



The rapid decay of a fine specimen of this tree, which grew at Co- 

 labah ai Bombay, is doubtless to be attributed to the same disease. — 

 This tne — one of the finest in western India — was forty-four feet in 

 circumference. In May 1840, it was vigorous and apparently healthy ; 

 a Uvr months after that time the large branches began to fall off and 

 the javages of disease proceeded with great rapidity. On examina- 

 tion the decayed portions were found to be perforated in all direc- 

 tions, like the one seen by Adanson, by the larvae of a beetle, which 

 were i">ducing the whole to a powder resembling saw-dust. Both the 

 larva aid the perfect insect are figured in the Bombay Times. The 

 former i described as being two and a quarter inches long, and three 

 inches in circumference at the thickest part. Some idea of the rava- 

 ges of thfcje larvae may be formed from the statement, that a piece of 

 the tree thee feet long and eight inches in girth, apparently healthy 

 and sound, vna found to be so thoroughly perforated that scarcely two 

 inches of sold wood could be found entire. 



