[39] There are no facts that show that this statement is not entirely imaginary. T. H. M. [40] The _italics_ are, of course, my own. T. H. M. [41] _Fundulus heteroclitus_, _Stenopus chrysops_, _Decapterus macrella_, _Menticirrhus macrella_, _Carassius auratus_, _Phoxinus funduloides_, _Noturus sp._, and a few others. [42] See Newport and Scudder. [43] Brindley, ’97. [44] Lepelletur, _Nouveau Bulletin de la Société philomatique_, 1813, Tome III, page 254; Heineken, _Zool. Journal_, 1828, Vol. IV, page 284 (also for insects, _ibid._, page 294); Müller, _Manual de Physiol._, Tome I, page 30; Wagner, W., _Bull. Soc. Imp. Natural._, Moscow, ’87. [45] The Sarasins have described several cases in _Linckia multiformis_ in which an old arm has one or more new arms arising from it. In one case (copied in our Fig. 38, _G_), four rays arise from the end of one arm, producing the appearance of a new starfish. In fact the Sarasins interpret the result in this way, although they state that there is no madreporite on the upper surface, and they did not determine whether a mouth is formed at the convergence of the rays, because they did not wish to destroy so unique a specimen--even to find out the meaning of it. There seems to me little probability that the new structure is a starfish, but the old arm has been so injured that it has produced a number of new arms. [46] For a review of the literature see Brindley, ’98. [47] I do not know whether this animal was kept long enough to make it certain that the legs do not regenerate. [48] A statement to the contrary quoted in Darwin’s _Animals and Plants under Domestication_ is doubted by Darwin himself. [49] The stork and the fighting cocks. [50] See Darwin, _loc. cit._ [51] The more generally accepted results are given in Virchow’s _Cellular Pathology_ and in Ziegler’s _Pathological Anatomy_. An excellent review of the subject down to 1895 is given in a summary by Ludwig Aschoff in the _Ergebnisse d. allgem. patholog. Morphol. und Physiologie_, 1895, “Regeneration und Hypertrophie,” in which there are two hundred and eighteen references to the literature. [52] Nothnagel gives a review of the subject down to 1886 in an article entitled “_Über Anpassung und Ausgleichung bei pathologischen Zuständen. Zeitsch. f. klinische Medicin._” 1886. Vols. X and XI. [53] Not, however, from the same litter. [54] _Internat. Beiträge zu wissensch. Medicin. Festschrift für R. Virchow_, Vol. II, 1891. [55] _Vorlesungen über allgemeine, Pathologie_, Vol. I, 1882. [56] _Handbuch._ [57] _Handbuch d. allgem. Pathologie_, 1879. [58] _Allgemeine Pathologie_, Vol. II, 1889. [59] _Über Endothelwucherungen in Arterien. Beitr. z. pathol. Anat._, Vol. VIII, 1890. [60] Haeckel (1870) first showed, in another medusa, that pieces produce new medusæ. [61] In rodents, however, the incisors continue to grow throughout the life of the animal.