778 
DR JOHN RENNIE ON 
It is noteworthy that many species occur oh plants, but, as has been shown, 
these, as far as known, do not possess the specialised characters of T. woodi, and for 
this reason it seems improbable that bees have recently become infected from flower- 
haunting forms. It is more probable that this took place through contact with 
other insects, possibly robbing visitors to hives. 
It may be remarked that along with my colleagues I have examined numbers of 
wasps, humble bees, earwigs, wax moths, Braula caeca, and although other mites 
were readily found upon the exterior, particularly upon the earwigs, the thoracic 
tracheae in all cases were found clear. 
The importance of finding answers to all of these questions raised is fully recog- 
nised by the Investigation I have the honour to direct, and the work is continuing 
with unabated vigour. I desire to take this opportunity of thanking my colleagues 
for the skill and ability with which they have aided me in the work so far accom- 
plished, and particularly Miss Elsie Harvey, my personal assistant, whose loyalty 
and diligence have been noteworthy. 
The foregoing researches have been carried out under the J oint-Committee upon 
Animal Nutrition of the University of Aberdeen and the North of Scotland College 
of Agriculture, with the aid of grants from the Development Commission, together 
with the generous financial help of A. H. E. Wood, Esq., of Glassel. To all of these, 
for their valuable assistance, and to the Local Advisory Committee, under Professor 
John Arthur Thomson, whose encouraging advice has been unfailing throughout, 
I desire to express the cordial thanks of my colleagues and myself. I also desire to 
thank the Carnegie Trust for help in connection with this research. 
Parasitology Laboratory, 
University of Aberdeen. 
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