Thus in 1877 Bütschli thought that ‘the chief significance of the formation of polar bodies lies in the removal of part of the nucleus of the egg, whether this removal is effected by simple expulsion or by the budding of the egg-cell.’ ‘Entwicklungsgeschichtliche Beiträge;’ Zeitschrift für wissenschaftliche Zoologie, Bd. XXIX. p. 237, footnote. Footnote 143: C. S. Minot, ‘Account, etc.;’ Proc. Boston Soc. Nat. Hist. vol. xix. p. 165, 1877. Footnote 144: E. van Beneden and Boveri have recently, quite independently of each other, made a more exact study of these ‘Polkörperchen’ (‘Centrosoma,’ Boveri). They show that nuclear division starts from these bodies, although the mode of origin of the latter is not yet quite clear.—A. W., 1888. Footnote 145: The existence of polar bodies in sponges has been recently proved by Fiedler: Zool., Anzeiger., Nov. 28, 1887.—A. W., 1888. Footnote 146: They have now been observed in many species, so that their general occurrence in insects is tolerably certain. Compare bibliography given in Weismann and Ischikawa, ‘Weitere Untersuchungen zum Zahlengesetz der Richtungskörper,’ ‘Zoolog. Jahrbücher,’ vol. iii. 1888, p. 593.—A. W., 1888. Footnote 147: Van Beneden, even in his last work, considers these bodies to have only the value of nuclei; l. c., p. 394. Footnote 148: I purposely abstain from using a more precise term, for the complicated terminology employed in spermatogenesis hardly contributes anything to the elucidation of the phenomena themselves. Why do we not simply speak of sperm-cells and spermatoblasts, and distinguish the latter by numbers when they occur in successive generations of different form? Moreover, all the names which have been suggested for successive stages of development, can only be applied to the special group of animals upon which the observations have been made. Hence great confusion results from the use of such terms as spermatoblasts, spermatogonia, spermatomeres, spermatocysts, spermatocytes, spermatogemmae, etc. Footnote 149: Fol, ‘Sur l’origine des cellules du follicule et de l’ovule chez les Ascidies.’ Compt. rend., 28 mai, 1883. Footnote 150: Roule, ‘La structure de l’ovaire et la formation des œufs chez les Phallusiadées.’ Ibid., 9 avril, 1883. Footnote 151: Balbiani, ‘Sur l’origine des cellules du follicule et du noyau vitellin de l’œuf chez les Géophiles.’ Zool. Anzeiger, 1883, Nos. 155, 156. Footnote 152: Will, ‘Ueber die Entstehung des Dotters und der Epithelzellen bei den Amphibien und Insecten.’ Ibid., 1884, Nos. 167, 168. Footnote 153: [It is almost certain that this vesicle is not derived from the nucleus, but from the cytoplasm of the sperm-mother-cell. See Douglas H. Campbell, ‘Zur Entwicklungsgeschichte der Spermatozoiden’ in Berichte der deutschen botanischen Gesellschaft, vol. v, 1887, p. 122.—S. S.] Footnote 154: