ISLE OF WIGHT DISEASE IN HIVE 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 weBe different. As before, the power of fiight 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 thitd 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, 



TEANS. ROY. SOC. EDIN., VOL. LII, PART IV (NO. 29). 118 



