G. H. F. Nuttall 
271 
infection followed the placing of the contents of a louse upon the con¬ 
junctiva in man. In nature, it might well happen that the soiled hand 
might travel to the eye and produce infection in a similar manner. 
The authors proved, moreover, that the spirochaetes are transmitted 
hereditarily to the offspring of the infected lice, for they found that eggs, 
laid 12 to 20 days after the infection of the parent lice, contained the 
spirochaete. The larvae issuing from these eggs likewise contained 
spirochaetes. By incubating the eggs at 28° C., the larvae hatched out 
on about the 7th day. When the eggs or larvae were crushed and 
inoculated into a monkey the latter became infected. 
We still lack detailed information regarding the behaviour of the 
spirochaetes in the lice and their offspidng; possibly it is similar to that 
recorded for S. duttoni in 0. mouhata. The main point may, however, 
be now regarded as established that lice (both P. vestimenti and 
P. capitis) transmit relapsing fever and are presumably the ordinary 
vectors in most parts of the world. These discoveries are naturally of 
the greatest practical importance, in view of the prevention of relapsing 
fever. 
I shall here digress to say a few words about the biology of lice 
infesting man, since you will find no precise information about it in the 
literature, except for the observations made by niy Demonstrator, Mr 
Cecil Warburton, in Cambridge. The latter has made the only accurate 
observations hitherto recorded for P. vestimenti in conjunction with 
an investigation we undertook on behalf of the Local Government 
Board, the results of which were published in their Reports for 1910. 
Mr Warburton found that P. vestimenti (= corporis) lives longer 
than P. capitis under adverse conditions. This is doubtless due to 
its living habitually on the clothing, whereas capitis lives upon 
the head where it has more frequent opportunities of feeding. He 
reared a single female upon his own person with self-sacrificing en¬ 
thusiasm, keeping the louse enclosed in a cotton-plugged tube with 
a particle of cloth to which it could cling. The tube was kept next to 
his body, thus simulating the natural conditions of warmth and moisture 
under which these creatures thrive. The louse was fed twice daily 
whilst it clung to the cloth upon which it rested. The female lived one 
month. She copulated repeatedly with a male which died on the 
17th day, and was replaced by a second male which likewise entered 
into copulation and survived the female. Copulation commenced five 
days after the female emerged and the process was repeated a number 
of times, sexual union lasting for hours. The female laid 124 eggs 
