592 CAROLINE B. THOMPSON AND THOMAS E. SNYDER 
uted to the winged forms is shown by the names given them by 
eighteenth- and nineteenth-century observers, such as ‘perfect 
insects,’ ‘true’ queens and kings, ‘royal pairs,’ etc. They were 
supposed to be the founders and progenitors of all colonies, 
while the less conspicuous forms with wing vestiges or entirely 
wingless, termed the ‘substitute’ or ‘complemental’ forms, were 
assigned the role of understudy, and were supposed to be waiting 
in a semideveloped condition, how patiently or impatiently we 
are not told, for some chance or disaster to remove one of the 
‘royal pair,’ whose place would then be filled from their ranks. 
Grassi ('93-’94) even went so far as to advance the hypothesis 
that these different reproductive castes, and also the sterile 
workers and soldiers, could be produced at the will of the colony 
by some unknown extrinsic means such as feeding, care, parasitic 
action, etc. 
More recent work! has shown that the fertile and sterile types 
as nymphs are internally differentiated at the time of hatching 
and that very early in their postembryonic development all the 
adult castes may be distinguished. This, of course, proves that 
the cause of the different types is of intrinsic or germinal origin, 
and disproves Grassi’s hypothesis of determining or changing 
the castes of termites by external means. 
As far back as the time of Lespés (’56) the nymphs of the two 
reproductive castes with long wings and short wing vestiges 
were known and described. These nymphs possessed long wing 
pads and short wing pads, respectively, and were termed by 
Lespés, ‘nymphs of the first form,’ and ‘nymphs of the second 
form.’ Lespés either was not acquainted with or did not refer 
to the nymphs of the wingless reproductive form. 
Grassi (93-94) recognized, in addition to the ‘true’ or ‘perfect 
insects’ with long wings, the two reproductive forms with short 
scaly wing vestiges and without any vestiges, but in reading 
Grassi one gets the impression that the distinction between these 
so-called ‘substitute’ and ‘complemental’ forms was vague, or 
at least seemed unimportant. The main point was that they 
should be ready to replace the ‘royal forms’ in case of need. 
1 Bugnion, 712, 713; Thompson, ’17, 719. 
2 
