Recent Work in Heredity 93 



organisms, such as snails, moths, water-fleas, 

 etc., we are met by the difficulty that few 

 figures on the subject are at present avail- 

 able. This is, indeed, a field in which far 

 more research is required. But as far as we 

 may venture an opinion at present, it seems 

 likely that the same law of inheritance holds 

 for mass-communities in all forms of life. 



It is found that the degree of resemblances 

 of grand-parents is about two-thirds that of 

 parents. 



Hence the inheritance from a grand-parent 



= ixf = '33- 

 While the inheritance from a great-grand-parent ; 



=*'33xf = '22. 



Thus the intensity of inheritance appears 

 to decrease in geometrical progression as we 

 go backward. 



Now, to summarize, though no physio- 

 logical theory has been formulated, it is 

 possible to arrive by pure statistics at the 

 degree of inheritance, and hence to predict 

 fairly accurately what the average offspring 

 of any pair will be like ; and this is what the 

 social reformer, the medical man, and even 

 the politician, really want to know when 

 dealing with the people in large masses. 



The newer biological theories appear in 

 their latest form to invert our process ; they 

 require a knowledge of the offspring and 



