164 Report of the President 



ANATOMY AND PHYSIOLOGY* 

 Ralph W. Tower, Curator 



The department has installed an exhibit entitled "From 

 Wing to Paddle." The specimens illustrate some of the 

 probable steps or stages in the transformation 

 of a wing which is used solely for flight, and 

 one — strange as it may seem — which is used only for swim- 

 ming. From this viewpoint birds could be divided into four 

 classes : those that fly high, soar and remain on the wing 

 for extended periods, as the vulture and the hawk; those 

 that fly rapidly and soar but little, as the swallow ; those that 

 fly heavily and do not soar, as the hen and turkey; those that 

 do not fly but use their wings to assist in rapid running, as the 

 ostrich, or for paddles in swimming, as the penguin. The 

 wings of birds are modified according to the shape, area and 

 structure of the supporting bones, while the arrangement and 

 size of the feathers play an important part in the function 

 of the wing. It is interesting to note that in the strong 

 fliers the muscles that lower the wing are more powerful 

 than those that raise it, while in the wing used as a paddle 

 the opposite is true. 



Another exhibit recently installed is a series demonstrating 

 the adaptation of limbs for swimming. A limb adapted to fly- 

 ing must be light and at the same time strong enough to 

 support the large surface of membrane or feathers needed 

 for flight. The bones of the wing of a bird are hollow, slender 

 and long ; on the other hand, a limb adapted to swimming must 

 be strong and furnish the support for a comparatively narrow 

 paddle. The foregoing characteristics are well illustrated in 

 the exhibit. 



A series of window transparencies illustrate the circulation 

 of the blood. The structure of the ventricles, auricles and 

 valves are shown by photographs taken from the normal heart. 

 The pulmonary and systemic circulation of the blood is de- 

 scribed by schematic drawings. 



* Under the Department of Anatomy and Physiology. 



