is provided by the late Joseph Barrell (1917) Vears 3,000,000 55,000,000- 65,000,000 9,000,000 140,000,000—180,000,000 18,000,000 360,000,000-540,000,000 30,000,000 600,000,000-—800,000,000 90,000,000 (Geikie, 1899) 400,000,000 (Geikie, 1899) 400,000,000 (Geikie, 1899) 400,000,000 (Geikie, 1899) I 200,000,000 I,400,000,000 tion is carried between centres, nor fed by reserves, and above it are termed “ synapsis.” We have first two blastomeres of the genus Rosa the fundamental instinct of self-preservation was solved by numer- ical step-by-step methods. Applications have been aided by an increase in the