Note 262 — Chapter XI
Reading edition
Ann. Sci. nat., i., pp. 110-14, 1824. Swammerdam is said to have observed the 2-celled stage in the egg of the frog (Bibl. Nat., 1752), and Rösel v. Rosenhof the same stage in the tree-frog (Hist. nat. ranarum nostratium, 1758).