The eyes of 7 buzzards (Buteo buteo) and 6 kestrels (Falco tinnunculus) were examined. The nodal point distances of the freshly enucleated eyes were ascertained, the cone intercenter distances of 3 retinal territories were measured with flat sections and the nodal point angles corresponding to these intercenter distances were calculated. The angles were used as a measure of visual acuity. The maximum visual acuity of the buzzard nearly corresponds with that of man, that of the falcon with that of the rhesus macaque. The resolving power of the extra-foveal retina is probably greater in hawks than in the primates taken for comparison. As to the microscopic anatomy the peculiarities of the hawk retina were represented: the richness of cones outside of the foveae, the highly developed inner nuclear layer, and shape and depth of the foveae. The superiority of the hawk eye to that of the primate in movement-seeing capacity and in fixing small moving objects is said to rest upon these structures. There were references that some morphological statements on the hawk eye should be investigated again. It is pointed out that physiologic investigations on visual acuity and movement-seeing capacity are necessary.
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