•><> Bee Disease 
slow and sluggish, may run rapidly, may tremble, present a hairless appear¬ 
ance, drag its hind pair of legs helplessly, may be subject to dysenteric dis¬ 
charges, or may impart a yellow colour to the interior of the hive by passing 
constantly a tiny threadlet of faeces. Possibly the varying manifestation may 
be due to the multiplication of bacteria of different species or of other parasites 
in the bowel of the affected bee. Whether the condition is sometimes due to 
infection it is impossible to decide. 
Again, the normal life of the individual bee may vary from eight weeks to 
as many months according to the activities of the colony, and it may be that 
organisms which do little harm in two months cause serious trouble where the 
necessities of the colony require the extension of the lives of its individual 
members for a longer period. 
The difficulty of tracing a connection between a disease and any parasitic 
organism that may be found in the bee becomes very real when the investiga¬ 
tion of disease is attempted. If, while the external conditions are favourable, 
the organism is fed to a colony as an experiment, the bees may fail to die or 
to develop symptoms; while if unfavourable conditions prevail at the time of 
the experiment, death may be due to unrecognised causes, such as infection 
with N. apis (see below). Apparently healthy bees, if prevented from flying, 
will sometimes develop symptoms (crawling with bowel distention) indistin¬ 
guishable from Isle of Wight disease. 
IV. Attempts to ascertain the Cause of Isle of Wight Disease. 
A. Bacillus pestiformis apis. 
The first to associate a definite causal organism with Isle of Wight disease 
was the late Dr Walter Malden (1909). He found no macroscopic appearances 
in the diseased bees that were not to be found in bees from healthy colonies. 
Microscopically, “no changes were discovered in the salivary glands, brain, 
fat-body, heart, tracheae, air-sacs, Malpighian bodies, or honey stomach.” 
Changes were found in the chyle stomach, however, and attention was con¬ 
centrated on that organ. In film preparations made from small portions of the 
chyle stomachs of diseased bees, teased out on glass slides and stained with 
methylene blue, a bacillus was found with darkly staining ends and a lightly 
staining central band, resembling Bacillus pestis in general appearance. This 
was suggested as having a causal relationship to the disease and the name 
Bacillus pestiformis apis was proposed. Cultures of this bacillus fed in sugar 
to bees did not appear to have any harmful effect and the view that it is the 
organism that caused the disease has been abandoned. 
B. Nosema apis. 
In 1907 Dr Enoch Zander (1911) discovered a protozoon in bees which 
was recognised as being closely related to Nosema bomb yds, a parasite which 
did enormous damage to the silkworm industry in France about the middle 
