[24] Verworn, General Physiology, pp. 102, 478: “Physiological chemistry has shown that between the two kinds of substance very essential chemical differences exist, which prove that living substance experiences in dying pronounced chemical changes. A widespread difference between the two consists in their reaction. The reaction of living substance is almost without exception alkaline or neutral, and with death changes usually to acid.... Physiological chemistry has shown similar changes in death in great number. All these facts prove that in the death of living cell-substance certain chemical compounds undergo transformations; hence substances exist in it which are not to be found in dead cell-substance.” [25] In 1892. An English translation of Bütschli’s work on Microscopic Foams and Protoplasm, by E. A. Minchin, appeared in 1894. The nucleus is really a form of protoplasm, chiefly differentiated from the ‘cytoplasm,’ or protoplasm of the cell, by containing a large amount of phosphorus. [26] The Cell in Development and Inheritance, 2nd edition, p. 9. [27] By J. A. and M. R. Thomson, 1904. [28] The Evolution Theory, II, p. 391. [29] _Ibid._, I, p. 368. [30] _Ibid._, I, p. 404. [31] The Evolution Theory, I, p. 353. [32] _Ibid._, II, p. 52. [33] But note the transition stage exemplified in the natural history of crystals (_vide_ p. 22). [34] “It has been Weismann’s great service to place the keystone between the work of the evolutionists and that of the cytologists, and thus to bring the cell-theory and the evolution-theory into organic connexion” (E. B. Wilson, The Cell, p. 13). [35] Prof. Wilson’s work on the cell (see note on p. 33) may be referred to for a comprehensive and detailed statement of all that is known at present on this subject. [36] According to Wilson (_op. cit._) this was guessed by Haeckel in 1866, and confirmed in 1884-5 by the almost simultaneous discoveries of O. Hertwig, Strasburger, Kölliker, and Weismann. [37] Sixteen have been counted in the human cell. A grasshopper has twelve, a lily twenty-four. The number is almost always an even one, but as with everything in Nature there are exceptions to the rule. [38] The process briefly described above is that of ‘mitotic’ division (μίτος, a thread, from the appearance of the chromosomes). Amitotic division, in which the cell and nucleus simply divide in two without the formation of chromosomes, also occurs under certain conditions, but is usually an abnormal or degenerative process (cf. Wilson, The Cell, pp. 116-119). [39] “Every animal appears as a sum of vital entities, each of which bears within itself the complete character of life” (Virchow, Cellular-pathologie, p. 12, 1858). [40] Weismann, The Evolution Theory, I, 251. [41] It is cast out into the cytoplasm—the substance surrounding the nucleus—where it degenerates (see Wilson, The Cell, p. 147). [42] _Amœbæ._ See p. 30. [43] The Evolution Theory, I, 265. [44] The Cell, p. 178.