86 
Biology of Pediculus liumanus 
The Number of Pediculi that may Infest a Person. 
Corporis. 
No enumerations have hitherto been made on highly infested persons. 
A medical friend, who attended confinement cases among the poorest 
classes in Edinburgh, once gave me a graphic description of the thousands 
of lice he beheld upon the body of a patient whose skin had a greyish 
colour owing to the huge numbers upon it. 
Iiase (1915, p. 13), who enumerated the lice on a very verminous 
Russian, was disappointed to find but 3800 in all stages of development, 
having expected a larger total. Peacock (1916, pp. 45-52) gives some 
interesting figures relating to British troops in the present war: of the 
infantrymen examined, 274 (95 %) were infested with an average of 
20 lice per 'man after 6 months’ active service; about 5 % harboured 
100-300 lice apiece. The number in some cases ranged from 168 to 
895 per man, and Peacock estimated that one shirt held 1355 lice and 
4260 nits, whilst another shirt contained no less than 10,428 lice and 
10,253 nits. To these cases I may add that in a shirt worn by an old 
woman on admittance to Lambeth Workhouse in June, 1915, we found 
ca. 600 lice in all stages coupled with innumerable nits (Lot 204). 
Capitis. 
The number of head-lice that may occur upon a person is enormous; 
no enumerations have hitherto been made in heavily infested persons. 
In the case of a paralytic woman, aged 45, who was admitted to 
a Poor House Infirmary in May, 1917, and whose hair and vermin were 
removed in my presence, I enumerated the lice and found 1004 present 
of all stages (208 adults and 796 larvae), coupled with innumerable 
nits; in the opinion of the sister in attendance, the case represented 
a very mild degree of infestation compared to others that have been 
admitted to the same institution. The woman’s clothes harboured a 
few corf oris (8 adults and some larvae) in addition. 
In June, 1917, Captain Orr of the Canadian Sanitary Corps, stationed 
in Surrey, sent me the pubic hair shaved from a soldier. The hair 
harboured 82 lice (76 adults and 6 larvae), 2544 unhatched and 2636 
hatched nits. The number of nits was estimated from a count made 
of one-quarter of the hair mass. The soldier was not infested with 
lice other than cafitis. 
