CONSTITUTION ANI) DEVELOPMENT OF TERMITES. 2638 
when also the thirteenth joint becomes pilose ; then a fourteenth 
joint is developed, and the whole fourteen are always found to 
be pilose in examples of 7 mm. and upwards in length. 
Iixamples with fourteen joints may exhibit evident traces of 
wings, which indeed may be already present in individuals 
with thirteen pilose joints, and a very indistinct rudiment of a 
fourteenth glabrous joint at the base of the third. But, on the 
other hand, examples with fifteen joints may be found without 
trace of wings. 
Those which have acquired wing-rudiments may be called 
larve of perfect insects. 
Undifferentiated larve, with thirteen or fourteen joints, as 
well as larve of perfect insects with thirteen (the fourteenth 
very imperfect) or fourteen joints may undergo a direct trans- 
formation into soldier larve with thirteen- or fourteen-jointed 
antenne, and from these originate the soldiers of medium 
size with the same number of antennal joints.! 
Lastly, undifferentiated larve with fourteen joints may 
either become larve of perfect insects without increase in 
that number, or they may remain unchanged till it has been 
increased to fifteen, all of which are pilose; and the latter 
condition may also be reached without change by the larvee of 
perfect insects. 
Both the undifferentiated larve and those of perfect insects 
with fifteen joints may give rise, without increase in that 
number, to the same kinds of forms that have been indicated 
for the larvee of fourteen joints,—soldier-larve, larve of royal 
substitutes, and, provided that they are as yet undifferentiated, 
larvee of perfect insects; and the last may acquire a sixteenth 
joint without increase of the wing rudiments (PI. 16, fig. 3). 
As a rule, therefore, the development of the sixteenth joint 
is accompanied by an increase in the wing-rudiments, so that 
the larva of the perfect insect becomes a nymph. 
I have found no undifferentiated larva with more than fifteen 
antennal joints; but, as I have said, we may have sixteen 
1 | have been unable to decide whether the number of joints is capable of 
increase in the soldier larve. 
