WINGLESS REPRODUCTIVE TYPE OF TERMITES 601 
In the nearly mature second-form nymph of 6 mm. (fig. 2) 
the distinguishing external features are the nearly colorless 
compound eyes, the shorter scale-like wing pads, extending 
backward only as far as the third abdominal segment, and the 
rather stout abdomen. ‘The legs are slightly heavier, notably 
_ the femora and the tibiae, than in the first-form nymphs. The 
number of antennal segments is eighteen. In both sexes genital 
appendices are present on the ninth abdominal segment. 
The venation of the short wing pads is similar to that found in 
the wing vestiges of the second form adult (fig. 4), and also to that 
of the first form. 
Internally, the chief difference between first- and second-form 
nymphs is in the size of the organs. In the nymph of the second 
form the brain and its main parts are on a slightly smaller scale, 
likewise the compound eyes, which also contain less pigment, 
and the frontal gland. 
The reproductive organs appear larger in the nearly mature 
second-form nymph than in the first (figs. 1, 2, 21, 22). In the 
female nymph of the second form the bulk of the ovaries is 
greater and the contained ova are larger, the oviduct has a 
greater width, and the seminal receptacle is nearly twice the 
size of similar organs in the first-form nymph. The colleterial 
gland also is larger in the second-form nymph. 
In the male nymph of the second form (fig. 25), the testes are 
more than double the size of those of the first form, the vasa 
deferentia are wider and more twisted, and the length and 
convolutions of the seminal vesicles greater. 
This is apparently not a morphological difference, but a 
physiological one, due to the earlier maturity of the sex cells of | 
second-form individuals. Sections of the abdomens of females 
of the three reproductive forms, in specimens of nearly maximum 
distention, show that the space filled by the egg tubes, and prob- 
ably the number of ova, is greatest in the first form, less in the 
second form, and least in the third form (Thompson and Snyder, 
"19, figs. 6 to 12). The difference in the mating habits of the 
first two forms is evidently correlated with the times of maturity 
of their reproductive organs. The first-form adults swarm, 
