BRAIN OF THE 'WHITE ANt' 583 



nymphs of the sexual forms, is in a less highly developed con- 

 dition, a condition that seems to be secondarily, indeed regres- 

 sively, modified, rather than primitive. In the area between 

 the mushroom bodies we find (fig. 7) a cup formed by base- 

 ment membrane, b.m., which, although smaller, is somewhat 

 similar in outline to that of the two nymphs just described. 

 The space within the basement membrane is not, however, 

 entirely filled by the cells of the frontal gland. The cells, 1, 

 occupy only the central part of the cup, the remainder consists 

 of a membranous network of mesenchjmi, 771s., similar to and 

 indeed continuous with the tentorial membrane which lies pos- 

 terior to the frontal gland and to the supraesophageal gangHon 

 in all castes. The cells of the frontal gland as shown in figure 

 7, 1, are cut in a plane parallel to their distal upper surfaces, the 

 cell bodies polygonal in outline and closely pressed together, 

 and only a few nuclei are present. In the following sections 

 from deeper portions of the gland, many more nuclei occur. 

 The cells are all of the slender elongated tjT^e, but mucli smaller 

 in every dimension than the slender elongated cells of the two 

 nymphs above described. None of the swollen secretory cells 

 are present. From the general appearance it may be inferred 

 that this gland in the worker is not only nonfunctional but 

 degenerate in structure. 



b. General discussion of the frontal gland. To summarize the 

 different structural and functional conditions of the epitheUal 

 cells of the frontal gland in the various forms of L. flavipes, we 

 find that in the soldier the frontal gland is evidently functional 

 and in active secretion. An external openmg is present and the 

 epithelial cells are all glandular, united in a syncytium contain- 

 ing a network of intracellular canals and covered b}' a porous 

 cuticula. 



In the true adult the frontal gland is probably functional. 

 An external opening is present above the gland; the gland has 

 enlarged since the last nj-mphal phase, and a cuticula resembling 

 that of the soldier is present upon the inner surface of the epi- 

 thelial cells. No statement as to the cells themselves can be 

 made now, since no sections of this gland have been studied. 



