APHILOTHRIX SIEBOLDI. 97 
in the lower right hand corner of Plate XXVII. And 
from that condition they advance through all shades 
of pink and red to a deep purple. 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, but 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 chamber. The outer layer is 
much 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 with those who consider the sweet substance 
as a means devised by the gall to entice ants to it and 
induce them to protect it; nor that the exudation is 
for the purpose of énsnaring 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. : 
