Cl. H. F. Nutt all 
173 
Repeated observations of lice under natural conditions has con¬ 
vinced me that they feed much more frequently than is generally 
supposed. Brumpt (1910, p. 550) states that corporis feeds mostly at 
night. Lelean (1917), no doubt confusing laboratory experiments, 
possibly those of Bacot, with what takes place in nature, states that 
lice feed twice in 24 hours. When I have .examined lice immediately 
upon their removal from infested persons, or lice maintained continu¬ 
ously upon the body under experimental conditions, I have been much 
struck by the fact that they are very rarely found gorged wdth blood. 
When they contain an appreciable amount of red blood, it is almost 
always in moderate quantity and frequently the contents of the very 
sparsely filled alimentary tract appear black. Again, when I kept lice 
continuously upon the person, T noticed that they started to bite at 
all times when I kept quiet. It is doubtless correct to state that lice 
bite most frequently at night, but it is certain that they bite frequently 
and at all times during the day, especially when the host comes to rest 
or there is little movement of the part of the body where the lice happen 
to be. 
The frequency with which lice feed is naturally dependent upon the 
rate of digestion, which in turn is influenced by temperature. Lice will 
feed much more frequently at body temperature than when kept cool. 
Entirely false conceptions may result from ordinary laboratory experi¬ 
ence regarding the feeding habits of lice, and it is to correct the tendency 
to such misconceptions that I lay stress on the subject. The only 
author who records experiments bearing on the matter is Hase (1915, 
pp. 72-74, cited by Muller), who maintained 11 lice at 37° C. arid saw 
7 of them feed again after an hour, whilst of 6 lice placed at 6° C., only 
2 fed after an interval of 9 hours. I would remark, however, that at 
such low temperatures the digestive processes are suspended, and, unless 
the insects had partaken of but a very modest meal, they would not 
again bite from hunger. 
The gorging of Lice. 
When lice become ravenous with hunger, they feed to excess. They 
fill their midgut to its utmost capacity with blood and the abdomen 
becomes proportionately swollen (Plate II). Not content, they may 
expel bright red, undigested blood from the anus. It occasionally 
happens that a few minutes after gorging, or at times later, that the 
insect assumes a pink and then a red colour all over owing to the rupture 
of the intestine and the diffusion of haemoglobin throughout its coelomic 
