9 o 



BIOLOGICAL LECTURES. 



Ziegler, 1 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 result- 

 ing principally in embryogenic and somatogenic variation 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 Lamarck- 

 ism. The distinction is mainly expressed in the terms 'ota- 

 genic' and ' kinetogenic ' of Ryder; for under Buffon's factor 

 the organism is passive, while under Lamarck's it is active. 

 Among others who have supported Buffon's principle are 

 Packard, Eimer, Cunningham, Ryder, and Ball. 



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. 2 First as regards evolution in relation to 

 heredity. The reversion phenomena as seen in human anatomy 

 wholly set aside Weismann's conception of evolution as the 

 selection of favorable and the elimination of unfavorable heredi- 

 tary 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 after an 

 enormous interval of time does actual elimination occur. Ab- 

 normal nervous conditions such as seen in Anencephaly are 

 accompanied by the revival of a large number of latent char- 

 acters. In Galton's language, patent characters become latent 

 in the course of evolution. 



Zoologie, 1886. Eroffnungsrede der ersten Versammlung der Anatomischen 

 Gesellschaft in Leipzig. Anat. Anzeiger, II, 1887. 



1 Ernst Ziegler : Die neuesten Arbeiten iiber Vererbung und Abstammungs- 

 lehre und ihre Bedeutung fur die Pathologie. Tubingen. 



2 J. T. Cunningham : The Problem of Variation. Natural Science, vol. Ill, 

 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.) 



