THE Hoc LovussE 671 
been traced between them and the brain, but they are in close association 
with the tracheoles of the commissure passing under its posterior part. 
While a study of the texts of Berlese (1909:588) and Schréder (1912-13: 
86) suggests that these bodies may be homologues of the “corpora allata” 
described by Carriére and Biirger in 1897, Heymons in 1899, Janet in 
1899, and others, a knowledge of their development is essential for their 
correct interpretation. A short distance behind the brain and approxi- 
mately above the esophageal ganglion, there has been seen in longitudinal 
sections of the head a ganglion in the course of the recurrent nerve, but 
no branches have been found issuing from it. This may be the hypo- 
cephalic or hypo-cerebral ganglion figured by Berlese (1909: 596). 
No attempt has been made to interpret a peripheral nervous system 
such as was described by Briithl (1871:477) in the pediculi infesting man, 
but if the nerve to the antennae be followed, it is seen to give off branches 
to the second and third segments which end directly under the cuticula 
in large multinuclear sensory cells similar to those at the termination of 
the labral nerves. In the terminal segment the nerve breaks up into 
branches corresponding in number to the blunt spinelike processes on 
the terminal sensory plate. Each branch terminates under its process 
asan oblong-ovate multinuclear sensory’ cell (Plate LIX, 9), but the actual 
connections between the cells and the processes have not been seen. 
Similar sensory cells have been seen in a few sections underlying the 
hairs of the abdomen. 
THE STOMODAEUM, MOUTH PARTS, AND SALIVARY GLANDS 
Writing of the clothes louse, Sikora (1916:22) says: “ Es gibt kaum 
ein anderes Insekt, iiber dessen Anatomie so lange gestritten wurde, 
und iiber das so viele voneinander ginzlich abweichende Meinungen 
gedussert worden wiren, wie die Laus.” Most of the literature is 
the outcome of investigations of the man-infesting pediculi, but in some 
instances more or less detailed comparative studies have been made 
on the hog louse. With a few exceptions workers have confined them- 
selves to the study of the mouth parts and their homologies, and this 
for two reasons: first, because in the middle of the last century a contro- 
versy was carried on as to whether lice possessed biting or sucking mouth 
parts, and secondly, because the systematic position of the group, long 
a matter of uncertainty, was thought to be dependent on the morphological 
