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The disease in animals was early recognized to have some of the 
features of diseases that are clearly infectious. Mention is fre- 
quently made of the fact that the disease may be carried from one 
animal to another by feeding the flesh of a diseased animal. In 1843, 
Heeringen wrote “ I am compelled to believe that trembles belongs to 
the anthrax family.” This was twelve years before the discovery 
of the anthrax bacillus. 
In 1877, Philips reports finding u spiral bacteria ” in the blood of 
a typical case, and the same organism, with cocci, in the urine of the 
same case. He encountered similar organisms in the urine of other 
cases. 
Gardner (1880) reported finding in the blood of a heifer suffering 
from the trembles, organisms “ that bore in size and behavior a 
striking resemblance to the form of bacteria called by naturalists 
bacilla subtilissima.” He found the same organism in the water of 
a spring that had supplied a family in which milk sickness was pres- 
ent. Dogs suffering from slows acquired by eating the flesh of the 
heifer also had the organism in the blood. He also found the organ- 
ism in milk. No bacteriologic investigations aided by the advantages 
of modern methods have been made upon this disease. 
Graff (1841) reported some very remarkable experimental work 
with trembles. He found the flesh of animals not to differ materially 
in appearance from that of sound animals. Salting meat he says does 
not impair its poisonous properties. The milk of a cow was poison- 
ous, as shown by feeding it to dogs for eight days after she was re- 
moved from the infected pasture ; but a test made a week later showed 
the milk to be harmless. He found small amounts of meat or butter 
sufficient to cause the disease. “ One ounce of butter or cheese or 4 
ounces of beef, either raw or boiled, administered three times a day, 
will certainly prove fatal within six days, and often earlier.” All 
these experiments were upon dogs and the flesh of his experimentally 
killed dogs was as poisonous as the beef that conveyed the disease. 
Graff found that treating the flesh with dilute sulphuric acid for 
two hours did not destroy the poison; even heating had no effect. 
He says butter heated “ to such a degree as to cause it to inflame lost 
none of its poisonous properties.” He failed to extract the poisonous 
agent from meat by prolonged boiling. He failed in attempts to 
communicate the disease “ by an inoculation with any portion of the 
body or secretions from infected animals.” These experiments lack 
confirmation. 
Milk cows seldom show any symptoms so long as they are regularly 
milked, even though they are secreting milk fatal to man and to other 
animals; in a herd the steers and heifers always show symptoms 
