84 MISCELLANEOUS PAPERS ON APICULTURE. 
ETIOLOGY (CAUSE) OF DISEASES. 
Every abnormal condition in the body of an animal which we 
know as disease has a cause which has brought about such a condi- 
tion. In most of the diseases of man and the higher animals compar- 
atively little is known of the cause. Likewise, and unfortunately, 
the same is true of bee diseases. Gradually but slowly new facts 
about all diseases are added to our knowledge, the unfortunate thing 
being that so many statements are reported as facts which have never 
been demonstrated to be true. 
In the study of the etiology of a disease and in the discussion of it, 
it is convenient to divide the causal factors into predisposing and 
exciting. Under the predisposing causes which may be considered 
as factors in bee diseases we have age, sex, race, heredity, climate, 
and preexisting disease. Under the exciting causes we may consider 
food and micro-organisms. 
To illustrate, let us consider the different factors just mentioned. 
predisposing causes. 
Age. 
In our experience with human diseases we have learned to expect 
scarlet fever, measles, mumps, and whooping cough more often in 
children than in adults; typhoid fever and appendicitis in young 
adults; and cancer in those more advanced in life. In bee diseases 
we expect European foul brood to attack larvae that are younger 
than those which suffer from American foul brood. We expect the 
so-called " pickled brood " to die just before or after capping, while 
paralysis is, as far as we know, a disease of adult life. 
Sex. 
Of some importance in the etiology of human diseases is the factor 
sex. Inflammatory rheumatism, gout, and diabetes, for example, 
occur more frequently in men, while goiter and hysteria are more 
frequent in women. In bee diseases we expect in American foul 
brood to find the worker larva? more often attacked than the drone, 
while in European foul brood this difference, if it exists, does so 
only to a slight degree. 
Heredity. 
You are all familiar with the fact that heredity is considered as 
an important predisposing factor in tuberculosis, cancer, gout, in- 
sanity, etc. It is interesting that in the so-called u pickled brood " 
there is some evidence which indicates that heredhw plays an im- 
portant role. 
