' BRAIN OF THE 'WHITE ANT' 579 



the following parts, which are present, with slight modifications, 

 in all the castes: (1) the epithelial cells, (2) the basement mem- 

 brane, (3) muscle fibers attached to the basement membrane, 

 (4) the fontanel nerve, an unpaired nerve running from the 

 frontal gland to the protocerebral lobes, and here described for 

 the first time. 



1. Nymph with long wing pads. The epitheUal cells (fig. 5, 

 1, 2) are of two kinds, of which the first far outnumber the 

 second: 1, long slender columnar cells, with rounded distal ends, 

 the distal cytoplasm taking a slightly deeper stain than the 

 proximal portion, and the large oval nucleus situated near the 

 base, 2, larger swollen cells whose cytoplasm contains vacuoles 

 and irregular masses of a deeply staining substance. The nuclei 

 of these cells are evidently basal but they are so crowded by 

 the adjacent cells that I have been unable to distinguish them. 



It will be noted that the lateral cells are more closely crowded 

 together than those on the floor of the gland, in the median line, 

 where the outlines of several cells maj' be clearly traced. It will 

 also be noted that the marginal cells of the gland are lower and 

 are directly continuous with the hj-podermal cells. Mitotic fig- 

 ures are present here and there among the cells of the frontal 

 gland in both nymphs, but no cutiqula on the distal surfaces of 

 the cells and no extracellular secretion have been observed. The 

 only cells which appear capable of producing a secretion in the 

 frontal gland of the nymph with long wing pads are the few 

 scattered swollen cells marked 2, and these seem to have not 

 yet discharged their secretion. This and the fact that there is 

 no external opening may indicate that the frontal gland is not 

 3'ct functional in this nymph. 



The basement membrane (fig. 5, h.m.) upon which the epi- 

 thelial cells of the frontal gland rest, is continuous with that of 

 the hypodermal cells and is considerably thickened along the 

 lower, ventral, surface. This membrane is composed of mesen- 

 chjTn cells and fibers and is beset with many irregular openings. 

 In some specimens it is very delicate but thick and firm in others, 

 and takes a deep pink stain with eosin, yellow with orange G. 

 The ventral surface of the basement membrane near the posterior 



