PHENOMENA OF INHERITANCE 295 



from a previous generation rather than inheri- 

 tance factors. These egg characters probably 

 appeared in the course of oogenesis under the 

 influence of paternal as well as of maternal 

 chromosomes; if so this is a case of Mendelian 

 inheritance in the previous generation or what 

 may be called "Pre-inheritance." Similar 

 phenomena have been described by McCracken 

 and by Toyama in silk-worms where several 

 egg characters seem to be non-Mendelian, but 

 Toyama has shown that they are in reality 

 Mendelian in the previous generation, this also 

 being a case of pre-inheritance. 



Somewhat similarly it has been found by 

 Correns, Baur, and Shull that the leaf colors 

 of certain plants are not inherited in Mendel- 

 ian fashion, but the chromoplasts, which pro- 

 duce the chromatophores (chloroplasts), are 

 transmitted from one generation to the next 

 in the cytoplasm of the egg cell and only rarely 

 through the male sex cell. If chromoplasts 

 are integral parts of a plant and undergo dif- 

 ferentiation or development this may be a case 

 of pre-inheritance ; if they are symbiotic organ- 

 isms it is an instance of the inclusion of foreign 

 bodies in the cytoplasm and not inheritance. 



