APFITLOTHRIX SIEBOLDI. 97 



in the lower right hand corner of Plate XXVII. And 

 from that condition thev advance thronsfh all shades 

 of pink and red to a deep pnrple. It is rarely, if ever, 

 green. 



The shape is generally conical ; some specimens are 

 oblate with the apex produced into a small papilla. 

 The lower portion is also conical descending deeply 

 into the zylem, and remaining there after the decay of 

 the superstructure. During growth many specimens 

 have the upper surface rounded, and when crowded 

 together they are considerably compressed, and there 

 does not appear to be any apex or papilla, l^ut both of 

 these ultimately develop and can be seen. 



The substance of the gall is composed of two layers. 

 The inner, yellowish in colour, thin, and woody, and 

 striated from the apex to the periphery. It encloses 

 a rather large larval chandler. The outer layer is 

 nuich thicker. It is composed of a soft and sappy 

 rind containing the red colouring matter, and from it 

 a slightly sweet mucilaginous substance exudes. It 

 may frequently be covered with a bloom. Ants are 

 very fond of the sweet substance, and build a dome of 

 earth over clusters of the galls. I have found several 

 very fine examples of this. Whilst recognising the 

 fact that the protection thus afforded prevents para- 

 sites and inquilines from attacking the galls, I do 

 not agree Avith those who consider the sweet substance 

 as a means devised l)y the gall to entice ants to it and 

 induce them to protect it ; nor that the exudation is 

 for the purpose of ensnaring unfriendly insects and 

 other small creatures. Repeated observations lead me 

 to the conclusion that ants are aware that by building 

 a dome, the galls are protected from premature 

 evaporation and drying, thereby securing a more 

 copious and lasting exudation for their exclusive enjoy- 

 ment. Galls not protected from the drying action of 

 midsummer heat in this way, or by dead leaves, moss, 

 or earth have less moisture in the rind than those which 

 are protected. 



7 



