MALDEN, FEBRUARY, 1909. 87 
9. The conclusion drawn is that in a knowledge of the causes of 
bee diseases lies hope for their control. 
MaLpENn, FEBRUARY, 1909. 
In 1909 Dr. Malden, of Cambridge, England, made a report? 
on his investigations of a disease which appeared on the Isle of 
Wight. A paper by Imms (p.79) discussing this disorder has already 
been considered. 
Malden went to the island in May, 1908, and by interviewing the 
_ bee keepers and inspecting colonies found that the disease had appar- 
ently quite died out. The disease had been seen, however, in March 
and early April of that year. After a short period of apparently 
complete absence the disease again appeared about the middle of 
June, 1908. 
Malden states that as a rule the disease causes greater losses during 
the summer than in winter. The reverse, however, has been noted 
at times. May and June are according to most observers the months 
during which the disease is usually most rapidly fatal. Infected 
colonies are not always destroyed. They may recover but are sub- 
ject to a later attack by the disease. 
Malden’s investigations into the cause of the disease include a 
study of the gross and microscopical anatomy of the diseased bee, 
together with a bacteriological study of it. In his bacteriological 
study one species was encountered to which, on account of its resem- 
blance to Bacillus pestis, the supposed cause of bubonic plague, he 
gave the name Bacillus pestiformis apis. The morphology, cul- 
tural characters, and pathogenic properties of this bacillus are 
given as follows by Malden: 
It is an aerobic, non-motile, Gram negative, non-acid-fast, short, broad bacillus, 
varying in its morphological appearances upon different media. No flagella could be 
demonstrated. On agar it grows fairly well, forming in twenty-four hours medium- 
sized (largest 0.1 cm. in diameter), round, white or slightly yellowish, smooth, glis- 
tening, flattened, dome-shaped colonies. On further growth the colonies do not 
increase much in size, and unless very thickly sown they show little tendency to 
coalesce. After twenty-four hours’ growth the bacilli are of medium length (1-1.5y), 
_ broad, and with distinctly rounded ends. Many of them are distinctly oval. They 
have a tendency to stain better at the ends than in the middle (polar staining). Occa- 
sionally the lightly staining central portion appears as a distinct band, especially 
when the organism is lightly stained. After seven days’ growth very little general 
change is noticed, though a few large involution forms make their appearance. On 
gelatin growth takes place rapidly in the form of colonies, resembling those produced 
onagar. ‘The organisms are more rounded than on agar, being distinctly oval in shape, 
and polar staining is not so marked. On potato a considerable raised cream coloured 
growth is produced in twenty-four hours at 37° C., which continues to spread. The 
bacilli are larger than when grown on agar, but the light central band is not quite so 
1 Malden, Walter, M. A., M. D., February,1909. Further repcrt on a disease of bees in the Isle of Wight. 
Journal of the Board of Agriculture, Vol. XV, No. 11, pp. 809-825. 
