June 21, 1924 
Morphology of the Honeybee Larva 
1177 
STOMATOGASTRIC NERVOUS SYSTEM 
In the bee larva, so far as known, this is the sole representative of the so-called 
sympathetic nervous system. It consists of the frontal or stomatogastric gan¬ 
glion and the nerves associated with it. The frontal ganglion is of relatively 
large size, in comparison with the imago, and is more or less pyriform in shape, 
its smaller end directed caudad (PI. 1, B and C, and 3, A, FtGng). It is situated 
above the oesophagus and just in front of the brain. Its sole connection with 
the brain is made by means of the frontal commissures or nerves ( FtNv ), which 
are rather stout bundles of fibers arising from the two sides of the ganglion near 
its anterior end. From this point they run laterad and caudad to the anterior 
faces of the two halves of the tritocerebrum, joining there the roots of the labral 
nerves, as already described. From the anterior end of the frontal ganglion a 
small nerve is sent off, sometimes called the “frontal nerve.” This term, how¬ 
ever, is objectionable, since it is also commonly applied to the commissures con¬ 
necting the frontal ganglion with the tritocerebrum. The nerve in question (PI. 
3, A, SPhyNv ) runs cephalad along the dorsal surface of the oesophagus to the 
epipharynx, where it divides into several branches, some of which go to the 
epipharangeal muscles. Twigs are also apparently sent to the tip of the labrum. 
In view of its" terminations, Janet (18) has termed the corresponding nerve in 
Myrmica rubra “nerf des muscles superieurs du pharynx situ6s en avant du 
ganglion frontal.” This descriptive term the writer for convenience ventures 
to abbreviate to “superior pharyngeal nerve” (SPhyNv). In Myrmica rubra 
there is another nerve to the posterior superior muscles of the pharynx. This 
nerve apparently is not represented in the bee larva. The posterior smaller end 
of the frontal ganglion is continued caudad as the stomatogastric or recurrent 
nerve (PI. 3, A, StgNv). This nerve passes caudad in close contact with the 
dorsal wall of the oesophagus, jneanwhile rapidly diminishing in caliber, to the 
posterior part of the head. Here it bifurcates, and a little farther caudad the 
two forks break up into branches too small to be successfully traced. In young 
larvae, and even in those as much as three days old, the two bifurcations of the 
recurrent nerve lead to flat discoid cell masses, closely applied to the sides of the 
oesophagus. These cell masses have been interpreted as the pharyngeal ganglia 
(86). In mature larvae they are no longer present, their places being taken by 
branches of the recurrent nerve, as stated above. 
HISTOLOGY 
The histology of the nervous system of the bee is too complex to be treated 
here in detail, but there are nevertheless certain outstanding features which 
deserve consideration. 
The outer neurilemma or sheath consists of a layer of cells, usually single, 
limited on each side by a delicate but distinct membrane, and forms the outer 
covering layer of the brain, the various ganglia, the connectives, and at least the 
roots of the peripheral nerves. In both its thickness and in the form of its com¬ 
ponent cells the neurilemma differs much in character at different pointy. On 
the dorsal surface of the suboesophageal ganglion, for example (PI. 2, B, SoeGng) 
the neurilemma (Nlm) often has the appearance of being only a single membrane, 
the two component membranes being actually brought very close together and 
the neurilemma cells being thin, flat, and spaced widely apart. At certain 
other points, in particular the posterior surface of the protocerebral lobes (PI. 2, B, 
Nlm), the neurilemma is, on the other hand, very thick, and its cells, irregular 
and mesenchymatous in form, are seemingly disposed in several layers. Usually 
the neurilemma cells form a regular epithelial layer (PI. 3, B and C, Nlm). Their 
cytoplasm, however, commonly presents a more or less shrunken and vacuolated 
