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J. Maynard Smith 



at the two temperatures were in fact identical, it would be 

 possible to predict the total lifespan of flies kept for varying 

 periods at the two temperatures. For example, a female 

 exposed for eight days to 30-5° soon after emergence would 



Table II 



Expectation of life at 30-5° c. 



be expected to have completed about half its expected life- 

 span, and therefore to have a further expectation of life at 

 20° of about 28 days. Experiments do not confirm this 

 simple additive hypothesis. 



Fig. 2 and Table III show the results of exposing young 

 adult females to 30-5° for varying periods, and then keeping 



