200 
Spirochaeta icterohaemorrhagiae 
(3) An animal injected with this virulent blood was by repeated inocula¬ 
tions of the Pasteur Institute immune serum protected absolutely, as has 
been shown by Martin, Pettit, and Yaudremer. 
(4) Blood and urine may be infective to animals, though careful examina¬ 
tion of the fluids by staining, dark-ground illumination, etc., may fail to show 
any spirochaetes (at least this was so in my hands); this may occur in other 
spirochaetal disease, possibly trench fever. 
(5) A white rat was found to be immune. 
We may conclude that the spirochaete of the type culture is the cause of 
the disease and that perfect protection in animals may be obtained against 
a very virulent infection by the use of the anti-icterohaemorrhagic serum 
prepared in the Pasteur Institute; a protection found by Fiessinger, Lervy, 
and others, which extended to human cases. (The serum has therefore been 
supplied to Naval units in Flanders.) 
The morphological characters of the organism have been fully described 
by Pettit and others, but under dark-ground illumination the long cultural 
form with its many minute turns and vesicular like body at one end are very 
remarkable, and the frequency with which these are interlaced together. 
Transverse fission appears very definite. 
The smears from the organs show generally abundant forms; these are 
much shorter and have fewer turns. At death the kidneys are seen to be 
greatly enlarged, dark, congested, and haemorrhagic. On section the 
malpighian capsules are frequently blocked with red blood cells, a glomerular 
nephritis. The tubules were blocked with red cells and all the blood vessels 
were distended. The spirochaete is abundantly present in the organ at this 
time. The livers were generally pale, and on section showed areas of degenera¬ 
tion of whole lobules, with small cell infiltration round the portal vessels. 
Finally I have to thank Prof. Louis Martin and Dr A. Pettit of the 
Pasteur Institute for providing me with the culture and immune serum, and 
Mr S. Mangham, M.A., for the micro-photographs reproduced in Plate IX. 
REFERENCES. 
L. Martin and A. Pettit. Bull. Soc. Med. Hdp., Paris, 1917, p. 1156. 
L. Martin, A. Pettit and A. Vaudremer. C. R. Soc. Biolog., 1917, Dec. 22, Yol. lxxx, 
p. 949. 
