554 CAROLINE B. THOMPSON 



c()ini)()se(l of many types of indivitluals, hut difforins greatly in 

 their degree of specialization and in intelligence. As the work 

 progressed it was found necessary to study the frontal gland in 

 detail, and it is now my intention to follow this paper with a 

 second, dealing with the development of the frontal gland and 

 the differentiation of the different types of brains in the recently 

 hatched nymj^hs. 



The only form to be discussed in the present paper is the 

 common termite, Leucotermes flavipes, Kol. As is well known, 

 this insect is not an ant, but belongs to the order Isoptera, family 

 Mesotermitidae, Holmgren ('11). The species, flavipes, was de- 

 scribed by Kollar ('37) ; the genus Leucotermes, formerly included 

 in the Linnaean genus Termes, was established by Silvestri ('01). 



In the northeastern United States there is only this one genus 

 and species of termites; in the southern states there is a second 

 species, L. virginicus, with three different genera in the Gulf 

 states, Snyder, and several other genera occur in California and 

 the southwest, Heath ('03). 



MATERIAL AND METHODS 



My material was collected in Wellesley, Mass., in May, 1915, 

 and June, 1916, beneath and within some old planks of wood. 

 The fixatives used were Bouin's Fluid, and Gilson's Fluid. The 

 former, however, is decidedly better for termite nervous tissue, 

 and three hours in the fluid gives a good fixation. Whole 

 mounts of all the heads were made by staining a long time, 

 twenty-four to thirty-six hours, in Conklin's picro-haematoxylin, 

 and then destaining for a day or longer in acid alcohol, clearing 

 in cedar oil and mounting with the frontal side up. The heads 

 of workers and of both types of nymphs, were embedded in hard 

 paraffin, three to four hours, and were sectioned at a thickness 

 of G/JL. The frontal or horizontal plane proved the most satis- 

 factory for sections of the head. In the case of the soldier, where 

 the chit in of the head is very thick, the brain was first dis- 

 sected out, under a dissecting lens, stained, embedded, and then 

 sectioned. This was also done for the worker, in addition to 

 sections of the entire head, the great hardness of the chitin making 



