118 CAROLINE BURLING THOMPSON 



tive nymphs, namely: the 'nymphs of the first fo:m/ with long 

 wing pads, and the 'nymphs of the second form,' with short wing 

 pads, which, it will be remembered, develop respectively into 

 two different adult castes, the 'true' royal pair, or adults with 

 long wings, and the neoteinic adults with short scale-like wing 

 pads But here, at first, a difficulty presented itself. Which 

 of these two varieties of the reproductive type is the prototype 

 of the nymph of the first form? and which of the nymphs of the 

 second form? It will be recalled (Thompson, '16, figs. 5, 6 a, 

 8, 10), that the nymphs of the first form have a large brain, a 

 large frontal gland, and pigmented compound eyes; the nymphs 

 of the second form have a smaller brain, in which the mushroom 

 bodies and the optic lobes are of diminished size, a smaller frontal 

 gland, and compound eyes almost devoid of pigment. But, 

 and here lay the difficulty, the sex organs of the nearly mature 

 nymphs of the second forms are larger than those of the first 

 form of similar age. Both Grassi and Feytaud make this state- 

 ment and the writer corroborates it. We are therefore con- 

 fronted with the difficulty of two prototypes, one with large 

 brain and large sex organs (figs. 4 a, 5 a), the other with smaller 

 brain and smaller sex organs (fig. 4 b) , while the older nymphs 

 have, in one case, a larger brain and smaller sex organs (nymph 

 of the first form), and in the second case a smaller brain and 

 larger sex organs (nymph of the second form). 



To solve the difficulty we must pass over the nymphs of the 

 first and second form to their respective adult stages; the 'true' 

 adults with long wings, and the 'neoteinic' forms with short 

 wing pads, and especially to the older queens of these two castes, 

 after they have undergone the characteristic post-adult growth, 

 and have become the enlarged queens which may attain a body 

 length of 14 mm. and 9 mm. respectively, Thompson ('16) and 

 Snyder ('16). 



It is true that the sex organs of the winged adults which are 

 ready to swarm are not so large in bulk as those of the 'neoteinic' 

 adults with short wing pads of similar age. It is also well known 

 that the sex organs in the enlarged egg laying queens with the 

 stubs of the former long wings are far larger than those of the 



