[1] “In November 1885, M. Maupas isolated an infusorian (_Stylonichia pustulata_), and observed its generations till March 1886. By that time there had been 215 generations produced by ordinary division, and since these lowly organisms do not conjugate with near relatives, there had of course been no sexual union.—What was the result? At the date referred to, the family was observed to have exhausted itself. The members, though not exactly old, were being born old. The sexual division came to a standstill, and the powers of nutrition were also lost” (_Evolution of Sex_, Geddes and Thomson, 1901, p. 177). [2] See, however, _Evolution of Sex_, p. 178, where a case is recorded of 458 generations of another infusorian apparently without degeneration. See also _The Cell_, by Dr. Oscar Hertwig (Sonnenschein, 1909), p. 292. [3] The _exchange_ of life-elements between two individuals is well illustrated in the case of the infusorian _Noctiluca_. Two Noctilucas, A and B, [Illustration: small diagram of conjunction of A and B] coalesce; and then later divide again along a plane (indicated by dotted line) at right angles to the plane of contact. Two new individuals are thus formed, and each Noctiluca has absorbed half of the other. Their activities are regenerated and they begin a new life. [4] As in Volvox; see _Evolution of Sex_, p. 138. [5] And we may say also here that it is even supposable that the special differentiation which we call male and female is only one out of many possible sex-differentiations—the important and main condition being that the differentiations, whatever they are, should be complementary to each other, and should together make up the total qualities and character of the race. [6] As sixteen for a human being, twelve for a grasshopper, twenty-four for a lily, and so forth. [7] For diagram and illustration of this whole process, see Appendix, _infra_, p. 289. Also see August Forel’s _The Sexual Question_ (English translation; Rebman, 1908), pp. 6 and 11; _The World of Life_, by A. R. Wallace, ch. xvii, p. 343; _The Plant Cell_, by H. A. Haig (Griffin, 1910), ch. viii; and other books.