70 
Psyche 
[March 
Each filament is made up of two or three cells in transverse section. 
The lumen in the filaments is well defined (Lu). Since the filaments 
do possess well defined gland cells that probably have an important 
part in venom synthesis, it is appropriate to call them filamentous 
glands rather than free filaments as has been done in the past. 
Originally, these filaments were called acid glands because it was 
believed that they produce an acid venom. This may be the case in 
the Formicinae but hymenopterons in other subfamilies of the Formi- 
cidae and in other aculeate families generally produce a basic venom. 
These filaments clearly are glandular in function, and they react 
significantly with tetrazolium salts in tests for enzymatic activity. 
Blum and Hermann (1969) reported faint reactions in the filaments 
of Pogonomyrmex badius (Latreille) with malate and a-glycerophos- 
phate. Although formazan deposition was apparent only in the distal 
part of the filaments in that investigation it is now believed that re- 
actions to produce formazan probably occurred throughout the fila- 
ments but were difficult to see in the thinner basal region. 
It is in the filaments or possibly in the associated fatty tissue that 
the beginnings of venom production probably occur. Fatty tissue in 
insects is a general center for intermediary metabolism. The citric 
acid cycle operates in the fat body. It can incorporate a wide variety 
of precursors into fat, protein and glycogen, and it functions much 
like a vertebrate liver in transmitting amino acids and making them 
available for anabolic processes in other tissues, in this case the fila- 
mentous glands and distal convoluted gland. An involvement with 
amino acids, which subsequently are built into venom proteins, takes 
place in non-formicine hymenopterons while other compounds would 
be utilized in formicines in the production of formic acid. 
At the point of junction between the filaments and convoluted 
gland (#1, Fig. 1 C; Jnct, Fig. 2 C) the cellular composition of 
the convoluted gland is similar to that of the filaments. However, 
cell type changes shortly beyond the attachment so that the con- 
voluted gland is composed of polygonal cells with smaller nuclei and 
more internuclear cytoplasm (Fig. 2D). This cellular change indi- 
cates that the filaments are quite active as glands themselves and that 
much of the chemical change of venom precursors already has oc- 
curred before they reach the convoluted gland. The cellular com- 
position remains much the same throughout the apical half of the 
convoluted gland. We have called this the cortex (Cor, Fig. 2 E) 
since there appears to be considerable glandular activity and hence 
continued production of venom components. 
