1895.] Search for the Unknown Factors of Evolution. 429 
tion connecting the environment directly with gonagenic 
and gamogenic stages, initiated by Virchow,” Kölliker,” 
Ziegler,“ Sutton, and others.. In a similar vein are the sugges- 
tions of Geddes, while those of Gerlach and Ryder direct our 
attention mainly to mechanical alterations in the embryonic 
stages of development. Botanists such as Vines, Detmer, and 
Hoffmann have pointed to the influence of environment upon 
gonagenic variation. Experiments of a general character 
resulting principally in embryogenic and somatogenic varia- 
tion have been recently carried on by Cunningham, Agassiz, 
and others, as illustrating the direct action of the environment. 
Followers of Buffon’s factor are also more or less identified with 
Lamarckism. The distinction is mainly expressed in the terms 
‘kinetogenic’ and ‘statogenic’ of Cope and Ryder; for under 
Buffon’s factor the organism is passive, while under Lamarck’s 
it is active. Among others who have supported Buffon’s prin- 
ciple are Packard, Eimer, Cunningham, Ryder, and Dall. 
This literature and so-called ‘evidence’ upon Buffon’s factor 
exhibits the greatest confusion of interpretation, and demon- 
strates that our conceptions first, as regards heredity, second, 
as regards variation under a changed environment, require 
thorough recasting.” First as regards evolution in relation to 
heredity. The reversion phenomena as seen in human anat- 
omy wholly set aside Weismann’s conception of evolution as 
the selection of favorable and the elimination of unfavorable 
hereditary variations; in other words, of selection acting 
directly upon the germ-plasm. These phenomena indicate 
rather that the direct process is not one of elimination but of 
suppression from the later stages of ontogeny, and that only 
2R. Virchow: Descendenz and Pathologie. Virchow’s Archiv, CIII, p. 1886, pp 
1-15, 205--215, 413--437. Ueber den Transformismus. Archiv f. Anthropologie, 
89, p. I. 
” Kölliker : Das Karyoplasma und die Vererbung. Zeitschr. f. wissenschaftl 
Zoologie, 1886. Eröffnungsrede der ersten TN der Anatomischen 
Gesellschaft in Leipzig. Anat. Anzeiger, II, 188 
“ Ernst Ziegler: Die neuesten. Arbeiten über Vererbung und eye seas 0 
lehre und ihre Bedeutung fiir die Pathologie. Tii 
18 J, T. Cunningham: The Problem of Variation. Nairo Sieience, ‘el III, 
pp. 282--287. Also, Researches on the Coloration of the Skins of Flat-Fishes. 
Jour. Mar. Biol. Assoc., May, 1893. (See also Trans. Roy. Soc., 1892-3). 
