ISLE OF WIGHT DISEASE IN HIVE BEES— PAtttOLOGY. 763 



Malden (2) was of opinion that " the disease must be regarded as an infectious one 

 which primarily affects the chyle stomach." 



The latter states that in his investigations " no changes were discovered in the 

 salivary glands, brain, fat body, trachese, air-sacs, Malpighian bodies, or honey 

 stomach," but that "the chyle stomach in many cases showed marked changes in 

 section." Of these changes in the chyle stomach the present investigation has seen 

 little or nothing. Two exceptional cases have been noted where the epithelial lining 

 had been definitely invaded. 



Malden, as a result of his bacteriological work, suggested a "plague-like" 

 bacillus, called by him B. pestifo)-mis apis, as the cause of the malady. He, however, 

 made the suggestion with some reserve, and later, when his work had been over- 

 shadowed by the " Nosema theory," considered that toxins produced by various 

 species of bacteria played an important secondary role in the disease. 



There is, however, an underlying truth in his summing up : " The actual cause of 

 death is uncertain, but it is probably brought about by malnutrition, possibly 

 combined with the absorption of a specific poison and of the products of decomposi- 

 tion in the colon, and probably aided to some extent by the imperfect oxygenation 

 of the tissues, owing to the pressure exerted by the distended colon on the abdominal 

 air-sacs." 



Imperfect oxygenation, and possibly malnutrition and a toxic condition, are the 

 main factors in the disease as we see them to-day. 



In this paper it has been sought to outline those pathological facts which have so 

 far come to light, and to relate them as reasonably as possible to the action of the 

 parasite on the one hand and the symptoms of the disease on the other. Certain 

 points have been merely touched on and others left in doubt, but it is hoped that 

 further details will be soon forthcoming. 



There are many to whom my thanks are due. To Dr J. Rennie, who, as director 

 of the research, has been an inspiring leader throughout, I tender my warmest 

 thanks for help and advice and much personal kindness. My sincere thanks are 

 due to Professor T. Shennan and the staff of the Pathology Department, Marischal 

 College, Aberdeen, who have given me every facility for carrying out this work. It 

 was in the Pathology Department that the parasite was independently discovered 

 on the 11th May 1920, and the theory of its significance in the disease formulated. 

 I wish also to express my gratitude to Professor J. Arthur Thomson, Mr A. H. E. 

 Wood, and the members of the Joint Committee of the University of Aberdeen and 

 N. of Scotland College of Agriculture for all their interest and support. 



EEFERENCES TO LITERATURE. 



(1) Imms, J. Board of Agric, vol. xiv, !N"o. 3, June 1907. 



(2) Malden, Ibid., vol. xv. No. 11, February 1909. 



