A. Balfour 295 
1 c.c. of the urine was inoculated intraperitoneally into a guinea pig on 
January 19th, 1921. 
A rise of temperature was noted on January 24th but no other sign of 
illness was at any time observed. The temperature fell to normal on January 
29th and remained normal till February 9th when there was a further slight 
rise lasting one day. 
From this time onwards until the end of the period of observation, i.e. 
50 days from date of inoculation, the animal remained apparently in perfect 
health. It was killed on March 11th and the autopsy showed no signs of 
infectious jaundice. 
A saline emulsion of the liver, lung, kidney and suprarenal was inoculated 
intraperitoneally on March 11th into another pig, which died on March 22nd 
with typical post-mortem appearances of the disease after exhibiting the usual 
clinical symptoms. 
There appears to have been no chance of the first guinea pig having become 
infected subsequent to the inoculation as it was kept in a separate cage, 
this being the rule in the case of all the experimental animals save those 
inoculated from one source. It was the custom to keep those together in one 
cage and it is interesting to note that if one of these developed the disease it 
did not transmit infection to any of the others. 
Culture of Leptospira. 
For this purpose Wenyon’s modification of Noguchi’s blood-agar medium 
was utilised. 
Culture was employed chiefly for the purpose of maintaining the strain 
and thus saving guinea pigs. The leptospira grew vigorously in this medium. 
In 48 hours at 30° C. the cultures, taken from the heart blood and organs 
of infected guinea pigs, were found teeming with the organisms, which re¬ 
mained viable from two to three months. In early culture virulence for guinea 
pigs was fully maintained but after repeated subculture, although a charac¬ 
teristic febrile reaction and the appearance of jaundice followed inoculation, 
the animals survived. 
Even after a year’s subculture at weekly or monthly intervals these definite 
symptoms were forthcoming but, as stated, there was undoubtedly attenuation 
of the virus. 
Nothing not already recorded by other observers was noted as regards 
the morphology of the cultural forms. 
Mechanism of Transmission. 
The experiments as regards transmission can be divided into the following 
groups: 
1. Feeding experiments 
(a) With natural food infected with leptospira-containing material from 
guinea pigs dead of the disease. Urine and organ emulsions were used (3 cases). 
