CHARTS AND THEIR EXPLANATIONS. 



Chart XXII. 





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Chart XXII shows average normal rates of growth of male and female white 

 rats according to Donaldson and to Osborne and Mendel. In our experience the 

 female rat does not attain as large a size as in Donaldson's experiments. The growth 

 curves coincide until the animals reach an age of about 70 days. 



