1909.] Disease of Bees in the Isle of Wight. 815 



the first to be attacked, and later the young bees which had 

 not been out of the hive. 



(4) It has frequently been noticed that bees which have 

 robbed infected hives have suffered from the disease and have 

 conveyed it to hives up till that time not infected. On this 

 subject Mr. H. M. Cooper writes : "On the other hand, I have 

 seen scores of cases where robbers have caught it almost 

 directly and have been dying off rapidly in about a fortnight, 

 and in two or three cases swarms have entered diseased hives 

 and have all been dead in from twelve to eighteen days." 



(5) No satisfactory evidence has been brought forward in 

 support of any of the other hypotheses which have been 

 advanced to account for the disease, while more or less 

 weighty evidence can be urged against them. 



The opinion that the disease is infectious has gained ground 

 in the Island, for Mr. H. M. Cooper recently wrote: "I 

 cannot at present say in what way the disease is spread, but 

 I think most people favour the theory of direct contact— often 

 caused by robbing." 



Anatomical Investigations. 



In commencing my observations on the Isle of Wight disease, I 

 first endeavoured to ascertain whether, by careful dissections, any 

 characteristic lesions could be discovered in the internal anatomy of 

 the diseased bees sent to me from various affected localities. Mr. A. D. 

 Imms, the only investigator who has up to the present published any 

 account of the anatomical observations on bees affected with this disease, 

 writes as follows : — 



" The disease is eminently one of the digestive system, and might 

 be described as being a condition of enlargement of the hind intestine. 

 . . . The colon and the adjacent parts of the rectum are enormously 

 distended with a congested mass of material, consisting primarily of 

 pollen grains. . . . The distended colon exerts pressure on the large 

 abdominal air-sacs of the tracheal system, and so interferes greatly 

 with their function. The insect is therefore unable to expand them 

 with sufficient air, which is necessary for flight, and this feature, 

 coupled with the additional weight in the digestive canal, renders the 

 insect incapable, when badly diseased, of flying about." He shows 

 that the inability to fly is not due to paralysis of the wing muscles, 

 but states that in the last stage of the disease the bees do not seem 

 to have strength to move their wings at all. He further states that 

 " while the hind intestine is thus gorged with pollen, etc., the stomach 

 and the remaining portion of the digestive canal contain very little 

 solid matter of any description. Some amount of a dark coloured fluid 

 is present very often in the chyle stomach, but it is not distended 

 with it. The contents of the rectum and colon consist of pollen grains 



