Note 140 — THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM (continued 4)
Reading edition
They would not be “real exceptions” if Klebs (Arch. Entw. Mech. 24, 1907) were right in saying that both variations and mutations owe their existence to external agents. What is really proved by Klebs is the possibility of changing the type of a curve of variation and of provoking certain discontinuous varieties by external means. See also Blaringhem (Comptes rend. 1905–6, and Soc. de Biol. 59, 1905), and MacDougal (Rep. Depart. Bot. Res., 5th Year-book Carnegie Inst., Washington, 129).