[128] Morgan, T. H., Embryology of the Frog. New York.

[129] Crampton, H. E., New York Academy of Sciences, 1894; Kofoid, C. A., Proc. Am. Acad. Arts and Sciences, 1894, xxix.

[130] Conklin, E. G., Anat. Anzeig., 1903, xxiii., 577; Heredity and Environment in the Development of Man. Princeton, 1915, p. 171.

[131] Wilson, E. B., Science, 1904, xx., 748; Jour. Exper. Zoöl., 1904, i., 1, 197.

[132] The reader will notice the absence of “regula­tion.”

[133] Conklin, E. G., Heredity and Environment in the Development of Man. Princeton University Press, 1915. The reader is referred to this book for the literature and main facts on the structure of the egg; it should also be stated that Conklin’s book is one of the best introduc­tions to modern biology in the English literature.

[134] Conklin, E. G., loc. cit., p. 117.

[135] Loeb, J., Jour. Morphol., 1893, xiii., 161; The Mechanistic Concep­tion of Life. Chicago, 1912, p. 106.

[136] Driesch, H., Science and Philosophy of the Organism, i., p. 104.

[137] Herbst, C., Formative Reize in der tierischen Ontogenese. Leipzig, 1901.