DEVELOPMENT OF CASTES OF TERMITES. 



5, a, b. The fourth antennal segment, which in growing indi- 

 viduals is always the youngest, is short and bears very minute 

 hairs, and in one specimen bears hairs on one side only, indications 

 that this segment has been very recently cut off from the third, 

 probably since the time of hatching. 



Externally these young nymphs of Neotermes are still all alike, 

 for no differentiation in the size of the heads can be observed, but 

 internally they are differentiated into the two types of nymph 



FIG. 5. Neotermes eastaneus, a, head of young reproductive nymph, 1.8 mm. 

 long; b, head of young soldier nymph, 1.8 mm. long; c, egg. a, b, Leitz oc. I, 

 bj. 3; c, Leitz oc. 4, obj. i; reduced one third. 



found in the other Protermitidae, namely: the reproductive or 

 fertile type, with large brain, and large sex organs, and the soldier 

 or sterile type, with small brain and small sex organs. The heads 

 of these two types are shown in fig. 5, a, b. 



Nymphs 2. 6 mm. in length and with eleven antennal segments 

 have the heads differentiated into the small-headed reproductive 

 type with large brain, and the large-headed soldier type with small 

 brain. 



All four genera of Protermitidae are therefore alike in possessing 

 two types of nymphs at the time of hatching. 



