632 H. S. Jennings 



As Conklin ('08) has so well set forth in a recent address, 

 "the mechanism of heredity is merely the mechanism of differen- 

 tiation." The questions with which we have to deal are those as 

 to the nature of the determining conditions and of the processes, 

 by which the constitution of the cell changes. Perhaps the most 

 direct study of heredity possible in the Metazoa is such a study as 

 Conklin is making of the internal determining conditions in the 

 differentiating cells of the developing organism. When one comes 

 to the study of heredity in the Protozoa, this simply coincides with 

 a study of the determining causes of differentiation. 



Johns Hopkins University 

 Baltimore, Md. 

 March lo, 1908 



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of Paramoecium caudatum. Arch. f. Entw.-mech., 15, 139-186. 



'06 — The Protozoan life cycle. Biol. Bui., xi, 229-244. 

 Conklin, E. G. '08 — ^The mechanism of heredity. Science, xxvii, 89-99. 

 Jennings, H. S. '06 — Behavior of the lower organisms. 366 pp. New York. 

 Jensen, P. '07 — Organische Zweckmassigkeit, Entwicklung und Vererbung vom 



Standpunkt der Physiologic. 251 pp. Jena. 

 Kellogg, V. L. '07 — Darwinism today. 403 pp. New York. 

 Roux, W. '81 — Der Kampf der Theile im Organismus. Leipzig. 

 Tower, W. L. '06 — An investigation of evolution in chrysomelid beetles of the genus 



Leptinotarsa. Carnegie Inst, of Washington, Pub. 26, 320 pp. 

 Whitman, C. O. '99 — Animal behavior. Woods Hole Biol. Lectures for 1898, pp. 



285-338. 



