First description of the germinal vesicle in the embryo, “Purkynĕ’s vesicle” This is located on the spot of the yolk where the embryo develops. Later identified with the cell nucleus, this formed a bridge between the large avian egg and the small ova of other animals, stimulating the researches of von Baer (No. 477). Reprinted in his Opera selecta, Prague, 1948, pp. 1-25; 2nd ed. Leipzig, L. Voss, 1830, reprinted in his Opera omnia, vol. 1, pp. 195-218. English translation of 2nd ed., in Essays in biology in honor of Herbert M. Evans (1943).