466 NOTES. 



42 (i. 130). "The Plastid-theory and the Cell-theory."— 

 " Jenaische Zeitschrift fur Naturwissenschaft," 1870, vol. v. p. 

 492. 



43 (i. 138). Gegenbaur, " On the Structure and Evolution of 

 Vertebrate Eggs with Partial Yelk-cleavage." — " Archiv f. Anat. 

 u. Phys." 1861, p. 491. 



44 (i. 153). Ernst Haeckel, "On Division of Labour in Nature 

 and Human Life," in the collection of Lectures by Virchow- 

 Holtzendorf, 1869. Sect. 78 2nd edition. 



45 (i. 160). Monogony (Generatio neutralis). On the various 

 forms of asexual reproduction (Schizogony, Sporogony, etc.), cf. 

 " Generelle Morphologie," vol. ii. pp. 36-58. 



46 (i. 160). Amphigony {Generatio sexualis). On the various 

 forms of sexual reproduction (Hermaphroditism, Gonochorism, 

 etc.), see " Grenerelle Morphologie," vol. ii. pp. 58-69. 



47 (i. 168). Fitful evolution and gradual evolution. The 

 theory of fitful evolution has recently been developed especially 

 by Kolliker, who, under the title of heterogeneous generation, 

 opposes it to gradual evolution as maintained by us (" Zeitschr. 

 f. Wissens. Zool.," vol. xiv. 1864, p. 181, and " Alcyonaria," 1872, 

 pp. 384-415). This theory is distinguished by assuming entirely 

 unknown causes for the "fitful evolution of species," a so-called 

 "great law of evolution" (an empty word indeed!). On the 

 contrary, we see, with Darwin, in the facts of Heredity and 

 Adaptation sufficient known (partly inner, partly external) 

 physiological causes, which explain the gradual evolution of 

 species under the influence of the struggle for existence. 



48 (i. 170). Immaculate Conception never occurs in the 

 vertebrate tribe. On the other hand, parthenogenesis frequently 

 occurs among Articulated Animals (Arthropoda) (note 16). 



49 (i. 171). Fertilization of Flowers by insects. Charles 

 Darwin on " The various contrivances by which British and 

 Foreign Orchids are fertilized by Insects." Hermann Miiller on 

 " The Fertilization of Flowers by Insects, and the correlative 

 adaptations of both " (" Die Befruchtung der Blumen durch 

 Insecten und die gegenseitigen Anpassungen Beider "). A con- 



