BRAIN OF THE VhITE ANT' 591 



6. The frontal gland is a gland found in all the castes of L. 

 flavipes, situated on the postero-dorsal surface of the brain in 

 the space between the mushroom bodies. The gland is com- 

 posed of epithelial cells which are continuous with the hypo- 

 dermal cells, A nerve, termed provisionally the fontanel nerve, 

 runs from the frontal gland into the brain. 



In the ti-ue adult and soldier the frontal gland is evidently 

 functional; in the worker it is nonfunctional and degenerate in 

 structure; in the nymphs with long and short wing pads it 

 is evidently not j'et functional, a few cells are glandular in 

 appearance with contained secretion, the large majority of the 

 cells are slender and elongated and resemble sensory, visual, cells. 



7. The suggestion is made that the frontal gland may have 

 arisen phylogenetically from the ancestral median ocellus wliich 

 is now lacking in the termites, and that the 'fontanel' nerve 

 may be a vestige of the former median ocellar nervT. 



The arguments for this view are based upon the position and 

 the structural resemblances of the frontal gland and the lateral 

 ocelli, upon the presence of the 'fontanel' nerve in the same 

 frontal section in which the lateral ocellar nerves enter the 

 brain, upon the resemblance of the frontal gland cells of the 

 developing njmiphal phases to visual cells, and upon the facts 

 collected by Holmgren regarding a phylogeny of the termites 

 based upon the morphology of the frontal gland. 



WELLESLEY, MASS. 

 AUGUST 18, 1916 



THE JOURNAL OF COMPAUATIVE NEUnOLOCV, VOL 26, NO 5 



