The Air Sacs of the Loon

AT irregular intervals during the past 100 years, there have been reports on the methods of study, general structure, modifications, and functions of the avian respiratory system. Most of the work has been done with the Pigeon, Columbia livia (Muller, 1908; Gilbert, 1939) and the Chicken, Gallus gallus (Locy and Larsell, 1916; McLeod and Wagers, 1939). These and other references in the literature serve merely as an introduction to the study of functions and variations in structure of avian respiratory systems. The state of knowledge as to the extent and positions of the air sacs of the Pigeon and the Chicken and the various terminologies used are well-covered by the references listed above, and will not be reviewed. This report is the first of a series being prepared in an effort to augment and clarify our store of knowledge on the morphology of air sacs so that an overall comparative picture is possible. This work was started under the direction of the late Dr. Will Scott at Indiana