08 
THE STRUCTURE OE THE MOUTHPARTS AND ME¬ 
CHANISM OF FEEDING IN PEDICULUS HUMANUS. 
By Lieut. A. D. PEACOCK, M.Sc., R.A.M.C. (T.). 
(With Plate VI and 6 Text-figures.) 
In my previous paper on the body louse (1916) many points of morphological 
interest were necessarily left in abeyance and mention was made that certain 
statements in it were open to correction. Further work has rendered correc¬ 
tion possible. While working in France, to ascertain whether Pediculus 
humanus was a carrier of the spirochaete of Weil’s disease, opportunity was 
taken to investigate those organs of the louse in which the spirochaete might 
lodge and the afferent and efferent channels through which it might pass. 
The enquiry did not demonstrate the presence of the spirochaete in the body 
louse, but incidentally a detailed knowledge of the mechanism of feeding was 
obtained and is here presented. Since the main conclusions of this paper 
were reached (December, 1916) I have read Harrison’s paper, “ A Preliminary 
Account of the Structure of the Mouth-Parts in the Body-Louse,” and while 
much of the following verifies his statements, we differ on certain important 
points regarding the structure of the mouth-parts and musculature. 
Grateful acknowledgment is made for the assistance rendered by Professor 
G. H. F. Nuttall, F.R.S., Quick Laboratory, Cambridge, Mr A. W. Bacot, 
Entomologist to the Lister Institute, Mr Lloyd, Chief Entomologist to 
N. Rhodesia, Captain J. Shaw Dunn, R.A.M.C., the late Major Sidney 
Rowland, R.A.M.C. and Captain Adrian Stokes, R.A.M.C. 
Professor Nuttall, on my showing him my MS. and preliminary drawings, 
kindly showed me his preliminary drawings of serial sections of the head of 
the louse; Mr Bacot lent to me a slide of sections of the same region and, in 
addition, both gentlemen made helpful suggestions regarding the text and 
drawings. Mr Lloyd has kindly permitted me to express an opinion on one 
of his dissections. Captain J. Shaw Dunn’s practised technique was responsible 
for the best series of sections upon which my main conclusions are based, 
while the late Major Rowland and Captain Stokes generously placed at my 
disposal some of their own private material and apparatus. 
Technique. To obtain adult specimens with the mouth-parts extruded is, 
in my experience, largely a matter of luck. Hungry lice may be placed on the 
arm and allowed to feed freely and undisturbed for a few minutes. A few 
drops of chloroform poured quickly over the insects renders them helpless 
sufficiently long to enable them to be transferred to 5 % formalin. The 
