ORIGIN OF CASTES OF TERMITES 113 



and the majority of the egg cells are smaller (fig. 25). In both 

 types the ovarian tubules open into the sides of the oviduct, a 

 characteristic of termites, and unlike the higher insects. 



The testes are small in both types at the time of hatching, 

 but the slight size difference is in favor of the reproductive type 

 (figs. 26, 27). At this stage the testis has the general appearance 

 of an irregularly swollen but slender tube, which at its posterior 

 end is continued into the still more slender sperm duct. I am 

 unable to distinguish any difference in the size of the male germ 

 cells in the two types of nymphs at the time of hatching (figs. 26, 

 27). 



The neivly hatched 7iymphs of L. virginicus. The newly hatched 

 nymphs of L. virginicus are about 0.8 mm. long in preserved 

 specimens — I have not seen them alive — and externally are all 

 alike, but internally they are differentiated, as in L. flavipes, 

 into the reproductive and the worker-soldier types. 



The same distinctive characteristics prevail in the two types 

 of the two species (fig. 3 a, h). The reproductive type has the 

 greater brain, with large mushroom bodies, optic lobes and anten- 

 nary lobes, and larger sex organs; the worker-soldier type has 

 the smaller brain, with small mushroom bodies, optic lobes and 

 antennary lobes, and smaller sex organs. The antennae of both 

 types have nine segments, the third segment grooved and bare. 

 Phase 2. Nymphs with ten antennary segments, the third segment 

 entire and bare; body length, 1.2 mm. (figs. 8, 9).^ 



The differences between the brains of the two types are as 

 marked as in the first phase, although the mushroom bodies 

 of the worker-soldier type are increasing in size and are be- 

 coming more differentiated, in that the outer, pointed, lobes can 

 now be recognized. The individual of the reproductive type 

 from which figure 8 is drawn, has evidently been slightly com- 

 pressed either in fixation or after mounting. The position of 

 the antennae and the distance between the antennary lobes indi- 

 cates that there has been a slight horizontal compression of the 

 head, which makes the brain appear a little larger than that of 



^ The nymphs described in phases 2 to 6 belong to the species flavipes, unless 

 otherwise stated. 



JOURNAL OF MORPHOLOGY, VOL. 30, NO. 1 



