Caird states how interested he was in Ewart's letter which appeared in The Scotsman. He also discusses physical development and the transference of lines of thought between generations. He gives examples of his own family, and of other Scottish families.

Caird states how interested he had been to read Ewart's article in The Scotsman about experimental contributions to the theory of heredity. He provides example of cross-breeding from his own horses, cows and rabbits.