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V. — On Acari from the Lungs of Macacus rhesus. 

 By F. Martin Duncan, F.E.M.S., F.R.P.S., F.Z.S. 



{Read June 18, 1919.) 



One Plate and Two Text-Figures. 



The first case of Acariasis in the lungs of the Common Ehesus 

 Monkey (Macacus rhesus) to come under my observation was 

 during September 1918, when I was assisting Dr. J. A. Arkwright 

 in Trench Fever investigation at the Lister Institute of Preventive 

 Medicine. Since then I have been able to investigate a number 

 of cases from various other sources, and from these cases the 

 material shown under the microscopes this evening, and the 

 photographs, have been obtained. 



The presence of these Acari is generally revealed by small, 

 pale, whitish-yellow vesicles dotted about on the surface of the 

 lung, and varying in size from ^th to ^th of an inch in diameter. 

 On dissection these vesicles are found to communicate with small 

 bronchi, and to have thin fibrous walls, which are generally lined 

 internally with a layer of soft white or greyish-white debris, in the 

 midst of which the mites rest. Although these cavities are 

 commonly situated just beneath the pleura, they are also occasion- 

 ally found in the depth of the lung. The Acari are always most 

 numerous in the cavities just beneath the pleura, and from the^^e 

 "nurseries" they appear to wander into the small bronchi that 

 open into the cavity, and thence make their way deep into the 

 tissues of the lung, their presence in this situation having been 

 demonstrated in several batches of serial sections of lungs. 



On opening a vesicle the mites will generally be seen resting 

 with their legs apparently more or less embedded in the debris 

 lining the cavity. They begin to move about, however, very soon 

 after the vesicle has been cut open, and if left alone may be seen 

 to crawl about and enter the bronchi opening into the vesicle, and 

 to disappear from view. The debris within the vesicle seems to 

 consist chiefly of desquamated epithelial cells and leucocytes, with 

 minute crystals, possibly of haemoglobin. A few bacteria have 

 also been detected in smears. 



It is interesting to note that in all the cases so far examined 

 the presence of these Acari in the lung does not appear to have 

 caused serious illness or death — death in each case being due to 

 some other clearly defined cause. At the same time the presence 



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