ISLE OF WIGHT DISEASE IN HIYE BEES — PATHOLOGY. 
761 
this point of view of secondary importance, a fact which may explain the apparent 
vigour of many heavily infected bees. 
In order to obtain some idea of the effects actually arising from mechanical 
obstruction of the spiracles, a series of experiments were undertaken upon healthy 
bees. In these experiments melted paraffin wax was applied to the first spiracle of 
one or both sides of each bee in such a way as to give, on solidification of the 
wax, complete closure of the spiracular orifice without impairing the free play of 
the wings. 
Bees treated in this way were maintained in boxes and were examined at in- 
tervals. In each experiment ten to twenty experimental bees were employed, and 
parallel controls were kept under the same conditions. 
Upon closure of one spiracle the experimental bees at once lost the power of 
flight, but remained otherwise active in their movements, running quickly over the 
bench and beating the air with their wings. Upon the second and third days it was 
sometimes found that a proportion of the bees were capable of flight — which was, 
however, usually of very short duration. In these it is probable that the wax had 
become partially dislodged. The majority of the bees continued to crawl. After 
the lapse of several days these crawling bees became more sluggish in their move- 
ments, sometimes showing a tendency to drag their hind legs, and about the 
sixth to seventh day, bees were noted which showed a dislocation of the wings 
similar to that so common among bees crawling from Isle of Wight disease. 
About this time, too, some of the bees began to die : many were, however, maintained 
up to the beginning of the third week. During this period also a few of the control 
bees died, but the remainder retained the power of flight throughout. 
At intervals experimental and control bees were killed for examination. Both 
in the “ artificial crawlers ” and in those control bees which had not been given 
opportunity to void their faeces on the wing, the hind gut was found distended with 
faecal matter. At the end of the first week of experiment it was found that the 
thoracic musculature of the experimental bees showed, in many cases, atrophy of 
exactly the same type as had been found in infected bees. The degree of this 
atrophy and the number of fibres affected varied with the duration of the experi- 
ment. No such changes were noted in the control bees. 
In those experiments in which the first spiracles of each side were closed with 
wax, the phenomena were different. As before, the power of flight was at once lost, 
but after twenty-four to forty-eight hours the bees had developed a reeling gait and 
appeared to be continually falling over their own heads. It was seldom that any 
survived the third day. No muscle atrophy was to be discovered, death having 
supervened too rapidly for the accomplishment of this change. 
From these experiments it may be stated that : — 
Through closure of the first spiracle of one side, a condition of crawling is induced 
which bears a close resemblance in its symptoms to Isle of Wight disease, and that, 
TRANS. ROY. SOC. EDIN., YOL. LII, PART IV (NO. 29). 118 
