CHAP, xii.] SUMMARY. 193 



the processes of heredity. By their aid, the desired 

 equation was thrown into an exceedingly simple form 

 of approximative accuracy, and it became easy to 

 compare both it and its consequences with the varied 

 results of observation, and thence to deduce numerical 

 results. 



A brief account of the chief hereditary processes 

 occupies the first part of the book. It was inserted 

 principally in order to show that a reasonable a priori 

 probability existed, of the law of Frequency of Error 

 being found to apply to them. It was not necessary for 

 that purpose to embarrass ourselves with any details 

 of theories of heredity beyond the fact, that descent 

 either was particulate or acted as if it were so. I need 

 hardly say that the idea, though not the phrase of 

 particulate inheritance, is borrowed from Darwin's pro- 

 visional theory of Pangenesis, but there is no need in 

 the present inquiry to borrow more from it. Neither 

 is it requisite to take Weissmann's views into account, 

 unless I am mistaken as to their scope. It is freely 

 conceded that particulate inheritance is not the only 

 factor to be reckoned with in a complete theory of 

 heredity, but that the stability of the organism has also 

 to be regarded. This may perhaps become a factor of 

 great importance in forecasting the issue of highly bred 

 animals, but it was not found to exercise any sensible 

 influence on those calculations with which this book is 

 chiefly concerned.. Its existence has therefore been only 

 noted, and not otherwise taken into account. 



The data on which the results mainly depend had to be 



o 



