450 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
Age 1.5 bres. 
‘Age 6+ 2hrs. 
206 
Strength of the rocking response 
0 5 10 15 20 25 39 35 
Flight duration (minutes) 
Ficure 1.—The relation between the strength of the’rocking’response, measured as the num- 
ber of oscillations of the side-to-side movement performed, and the duration of a preceding 
period of forced, tethered flight for Automeris aurantiaca at 1.5 hours, and 6+2 hours 
after eclosion. 
phenomenon of specific age. All, or nearly all, animals undergo 
senescent change; all ultimately die; and the duration of life, or, at 
least, the average pattern of longevity, is a property that is char- 
acteristic of a given species. Yet in no animal group have the 
mechanisms responsible for these neatly adjusted limitations of life- 
span been worked out. 
At the beginning of July 1958, through the good offices of the 
Director of the Canal Zone Biological Area, Dr. Martin Moynihan, 
and aided by a grant from the U.S. National Science Foundation 
to the Smithsonian Institution, fieldwork on the Central American 
Saturniidae was finally started. 
