CONSTITUTION AND DEVELOPMENT OF TERMITES. 265 
rudiments are reabsorbed until hardly a trace is discoverable 
with the microscope. This origin of the soldier from the 
nymph is certainly infrequent. 
Nymphs with seventeen antennal joints may become imagos 
without increase in that number, or with an antecedent addition 
of one or even two joints; and the perfect insects may thus 
exhibit antennz with from seventeen to nineteen pilose joints, 
a numerical difference which has no relation to sex. Nymphs 
with seventeen to nineteen joints may be also transformed to 
royal substitute larve, but I do not believe that those with 
eighteen or nineteen joints can become soldiers, as I have never 
found so large a number in any example of that caste. 
The change from the nymph to the imago is accompanied 
by the development of pigmented compound eyes, while the 
wing-rudiments, from being vertical and closely appressed to 
the sides of the body, become dorso-lateral at their origin, 
nearly horizontal, and divaricate at the apex.1 These speci- 
mens have at last reached the adult stage (imago), and (Pl. 16, 
fig. 6) possess fully developed wings; at first white, they 
gradually become black and capable of flight. 
It will be seen from this account that examples with a 
number of antennal joints varying from twelve to seventeen, 
and therefore of very different lengths, can be transformed to 
soldier larve, and consequently to soldiers; and that those in 
which the number of joints varies from fourteen to nineteen 
may become larvee of substitute royal forms. The latter larve 
are not easily separable from the others; but in those with 
from fifteen to seventeen antennal joints the pigmentation of 
the compound eyes is evident. But it is absent or very scanty 
in substitute larve with fourteen, and some with fifteen joints. 
Ocular pigment is sometimes present in nymphs with seventeen, 
and always in nymphs with eighteen or nineteen antennal joints 
before their metamorphosis into substitute royal larve. 
The larvee of perfect insects or young nymphs are customarily 
selected for development into substitute forms (Pl. 16, fig. 14), 
1 In these specimens the wings have really reached their full development, 
but are enclosed in a chitinous sheath. 
