196 Heredity and Social Progress 



The primary avenue of the exit for surplus 

 energy is reproduction. The simplest organ- 

 isms have no other means of utilizing it. The 

 secondary avenue for the exit of a surplus is 

 growth the duplication of parts which re- 

 main united in a whole. But the end is not 

 here, for when energy goes out in growth, it 

 must finally come back to reproduction. All 

 vital series, no matter how long, must culmi- 

 nate in reproduction. 



Of these indirect series there are two kinds, 

 simple and complex. In a simple multicel- 

 lular organism the series is growth, folds, ovaries, 

 and sex products. Growth if rapid is unequal 

 and its inequalities are the cause of folds, which 

 become ovaries from which sex products are 

 emitted. Complex organisms have no more 

 elements than these, but they are united in 

 more striking combinations. The series now 

 becomes growth, folds, ovaries, renewed growth, 

 enclosed sex products, nerves, emotions, reduc- 

 tions, regenerations, renewed growth, ovaries, 

 exposed sex products, and then reproduction. 

 These complex multicellular organisms differ 

 from simple organisms in that they are double. 



