Ælurostrongylus abstrusus, discovered by Mueller in the lungs of cats in Germany, has since been reported from various other countries in Europe. In many cases the diagnosis has been based on the recovery of the characteristic larva but occasionally a few adults have been found. These have generally been isolated by teasing up the lung substance in normal saline and then searching through the fluid by means of a low-powered objective or a dissecting microscope. The technique adopted by the writer was to cut thin slices of lung tissue, to compress these between two ordinary glass slides, and to examine them with an inch objective. The larvæ could be easily found in the expressed fluid and adults could be noticed as dark masses in the lung itself. When seen, the adults were removed by means of dissecting needles.