146 Spirocliaetosis 
These experiments tend to show that in order to obtain a permanent 
strain of Russian spirocliaetosis, capable of being easily transmitted from 
one mouse or rat to another, it is first necessary to pass the organism 
through a monkey, as has been done by Uhlenhuth, Haendel, and 
Fraenkel. 
Conclusions. 
(1) European relapsing fever, caused by Sjnrochaeta recurrentis, 
can be transmitted directly to mice and rats. The infection does not 
appear to last more than two days (Gabritschewsky). 
(2) As open and spirillar forms, corkscrew shapes and lashing 
spirochaetes with trypanosome-like movements, according to different 
circumstances, maj^ appear in all the three strains I have observed, there 
is no possibility so far of distinguishing morphologically S. recurrentis 
from duttoni, or novyi. 
(3) The marked distinguishing feature between Russian relapsing 
fever and Central African tick-fever is caused by the vague factor called 
“ virulence,” and this is decidedly greater in the case of S. duttoni. 
(4) On several occasions it was possible to reinfect rats and mice 
with quite small injections' of relapsing fever blood. A marked 
immunity as a result of previous infections was therefore not present in 
these cases. 
(5) In Moscow, relapsing fever appears to be transmitted by 
Pedicidus vestimentorum. 
(6) Peculiar ring forms, containing granules, were detected in mice 
on several occasions, possibly as a result of beginning degeneration in 
S. recurrentis. 
LITERATURE. 
Balfour, A. (1908). Spirocliaetosis of Sudanese Fowls. Third Report of the 
Wellcome Tropical Research Laboratory., 38. 
- (1911). The Spirocliaete of Egyptian Relapsing Fever. Is it a Specific Entity ? 
Fourth Report of the Wellcome Tropical Research Laboratory, 67. 
Bergey, 1). H. (1911). Studies on spirochaetal infections. U7iiv. of Penn. Med. 
Bull. XXIII. 617. 
Bosanquet, W. (1910). A note on a spirocliaete present in ulcerative granulomata 
of Australian natives. Pa^-asitology, ii. 344. 
—— (1911). Spirochaetes. London, Saunders Co. 2>. 38. 
Bousfield, L. (1910). Observations on human siiirochaetosis in the Sudan. 
Journ. Roy. Army Med. Cmps, xv. 444. 
