94 HISTORICAL NOTES ON BEE DISEASES. 
During the following decade there continued to be different opinions 
entertained as to the classification of the infectious brood diseases. 
Many bee keepers were convinced from their experience with the 
diseases of the brood that there existed two distinct infectious dis- 
orders (p.60). Bya more careful study of these diseases it has been 
shown positively that the brood is attacked by more than one infec- 
tious disease. 
These diseases as understood by the writers of this bulletin are 
briefly discussed on pages 11 and 12. | 
The classification of the adult bee diseases is yet very unsatisfac- 
tory. 
THE CAUSES OF BEE DISEASES. 
As exciting causes of bee diseases different workers have from time 
to time suggested different agents. 
Schirach (1771) (p. 13) suggested two causes for foul brood—improper 
food as one, and a fault of the queen as a second. 
Leuckart had at first inclined to the view that the infectious foul 
brood was due to a fungus, but from his observations made in 1860 
(p. 14) he arrived at the conclusion that this was not true. 
Molitor-Mthlfeld (1868) (p. 15) attributed the cause to a parasitic 
ichneumon fly, Ichnewmon apium mellificarium. 
Preuss (1868) (p. 15) and Schénfeld (1873-74) (p. 16) were inclined 
to believe that an infectious form of foul brood was due to a fungus, to 
which the former gave the name Cryptococcus alvearis. 
Cheshire (1884) (p. 21) and Cheyne (1885) (p. 34) were inclined 
to believe that foul brood was due to a bacillus, Bacillus alvet. 
The same disease which Cheshire and Cheyne studied came to the 
attention of William R. Howard in 1900 (p. 46), and he declared that 
the cause of it was a bacillus, to which he gave the name Bacillus 
milir. “eke 
Recent work (p. 81) has proven that American foul brood has as 
an exciting cause a specific bacillus, to which the name Bacillus larve 
has been given. 
The writers of this bulletin believe that. the causes for the other 
bee diseases have not as yet been satisfactorily demonstrated. 
