DEVELOPMENT OF CASTES OF TERMITES. 



383 



of eggs, corresponding to the two different types of nymphs 

 which are hatched. Since this paragraph was written further 

 study of living eggs enables me to state with certainty that there 

 are marked differences in size in the living eggs of a given species 

 and, furthermore, among eggs in the same phases of develop- 

 ment. 



d 



FIG. 2. Calotermes n. sp., newly hatched nymphs, a, head of reproductive 

 nymph with large brain; b, head of soldier nymph with small brain; c, testes, repro- 

 ductive nymph; d, testes, soldier nymph. Oc. 6, obj. 16, reduced one third. 



The newly hatched nymphs of Calotermes n. sp. are 1.6 mm. 

 long, with nine antennal segments, the third segment entire and 

 bare. In size, shape and general external appearance these 

 newly hatched nymphs are all alike, but, as in the genus Retlculi- 

 termes, they are separable by means of internal structures into 

 two types: (a) nymphs with a large brain that almost fills the 

 cavity of the head, large sex organs, and a white dense abdomen, 

 the reproductive or fertile type (Fig. 2, a, c}\ and (6) nymphs 

 with a smaller brain that does not nearly fill the head cavity, 

 smaller sex organs, and a transparent abdomen, the soldier, 1 

 or sterile type (Fig. 2, b, d}. 



When the Calotermes nymphs have attained a body length of 

 1.8-2 mm. a marked difference in the size of the heads is noted, 



1 The worker caste is lacking in the genus Calotermes. 



