One of the most intriguing characters in Treasure Your Exceptions is Robert Heath Lock. In a letter to Beatrice (1917), Bateson said he had begun writing an obituary, but this has not yet surfaced. Lock, known to his friends as 'Bertie,' met Bella Woolf on the boat out to Ceylon, where he was Assistant Director of the Royal Botanic Gardens at Peradeniya. She was visiting her colonial administrator brother, Leonard Woolf, who later would marry Virginia Stephen. So Lock became Virginia Woolf's brother-in-law.

    Lock's textbook Variation, Heredity and Evolution (1906) spread the Mendelian message, and H. J. Muller later acknowledged its influence on himself and his "fly room" colleagues. Lock died in 1915 of a heart attack after influenza and the 4th edition (1916) was brought out by Bella with updating by Leonard Doncaster, who died in 1920 at the age of 42. Thus, two of the youngest and most dynamic members of the Bateson "pack" were not available to continue his work.

    To the 4th edition Bella attached a brief biographical note that, surprisingly, does not mention Bateson. While there was much correspondence between Bateson and Lock, the Bateson letters to Lock have disappeared, but we can judge their content from Lock's replies. Lock may have been better able to read the German literature than Bateson, and his praise for Hugo de Vries (whose early works were in German) may not have endeared him to Bateson. He read the English literature deeply, and his father, the Bursar at Caius College, Cambridge, was quick to respond to his requests for books to be sent to Ceylon.

     In later editions of Variation, Heredity and Evolution the works of Samuel Butler and George Romanes were cited. In 1921 Bella married Tom Southorn, a colleague of Lock, and returned to Ceylon.