44 



TYPES OF MENDELIAN HEREDITY 



like the age of the individual, also be considered as 

 influences external to the hereditary factors which 

 affect the development of characters. And not only 



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Fig. 20. — Leptinotarsa signaticoUis (above), and L. undecimlineata 

 (below), with their full grown (Z?) and second stage (C) larvae to the right 

 of each. (After Tower.) 



do regional peculiarities influence characters, but 

 special regions are usually required for a given factor 

 difference to manifest itself, just as certain tempera- 

 tures or ages may be necessary. Thus when we 



