64 
Lice and Disease 
discoverable spirochaetes. In their experiments, in which they infected 
men and monkeys with lice crushed 1-8 days after the insects had fed 
on spirochaetosis blood, it was noted that no spirochaetes were discoverable 
microscopically in the infective material. 
The authors confirm the observations of Nicolle and his colleagues 
that spirochaetes reappear in lice after an interval of about eight days; 
they rightly lay stress upon the results of their experiments conducted 
in 1908-11 which demonstrated that lice harbouring no visible spiro¬ 
chaetes, are infective. It is therefore evident that spirochaetes must 
assume a minute form during the apyrexial period in man, and during 
a period lasting about eight days in the louse, after the latter has fed 
on spirochaete-containing blood. The authors conclude that spiro¬ 
chaetes undergo a cycle of development both in man and the louse, 
this being in accord with the view held by a number of authors, including 
the writer, that spirochaetes are Protozoa. 
Bisset- (19. i. 1914, pp. 114-119), who studied relapsing fever in the 
Meerut Division, India, examined 663 lice, taken from patients, and 
found 26-3 % .thereof infected; 100 control lice gave a negative result. 
He only found spirochaetes in the insects’ gut and coelomic cavity, 
and rarely found many after the lice had starved for 5-6 days. Lice 
infested all the families which suffered from relapsing fever, and the 
epidemiology of the disease pointed to lice being the only carriers. 
The author ignores the work already carried out by Sergent, Nicolle, 
and their colleagues in Africa. 
Toyoda (1914, pp. 313-320), likewise ignored the work of the French 
observers. He fed body-lice on mice whose blood harboured S. re¬ 
currentis (Russian strain); he afterwards maintained the insects at 
20-25° C., and fed them once daily upon a monkey which did not become 
infected. The spirochaetes in the lice were active for 4-5 hours, but 
they disappeared from the gut after 24 hours. A few were present 
in the coelomic cavity up to the seventh day, as demonstrated in stained 
sections. Crushed lice were infective for mice up to three days after 
they had fed on infective blood. He believed that spirochaetes multiply 
in the coelomic cavity and he found them in the region of the head in 
lice. Toyoda’s results, in the main, confirm those of the French ob¬ 
servers, but his experiments were very much less detailed. 
Nicolle and Blanc (15. vi. 1914, pp. 1815-1817, preliminary note, 
and 1. xn. 1914, pp. 69-83) next reported upon five series of experi¬ 
ments in each of which 20 lice were fed upon a monkey with relapsing 
fever, the lice being subsequently fed upon healthy animals or men 
