THEORY EVOLUTION. 
Gen. Sub. 9 
using, C. Die Bedeutung der Konstitution des Korpers und die 
Vererbung erworbener Eigenschaften fur die Enstehung der Arten. 
Humboldt, vii, 9, pp. 336-341. 
Durand, J. P. Genese naturelle des formes animales. Rev. Sci. xli, 
pp. 741-762. 
Dyer, W. T. Tiiistleton. Openiug Address of Biological Section of 
British Association. Nature, xxxviii, 985, pp. 473-480 ; Rep. Brit. 
Ass. Iviii, pp. 686-701. 
. Mr. Romanes’s Paradox. A Letter. Nature, xxxix, 992, pp. 7-9. 
— — . Mr. Romanes on the Origin of Species. Letter to Nature, xxxix, 
997, pp. 126 & 127. 
Eimer, G. H. Th. Die Enstehung der Arten auf Grund von Vererben 
erworbener Eigeuschaften nach den Gesetzen organischen Wachsens. 
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“ Tho origin of species through the inheritance of acquired characters, 
according to the laws of organic growth.” (1) Variations occur along 
definite determinate lines of development, and in a few directions. (2) 
The interaction of the external forces and the physico-chemical changes 
of the growing organism is the basis of variation. (3) As organisms 
progressively develop in accordance with “the laws of organic growth,’ 
literally growing into their places, species are but the stations in the 
progressive march. (4) “ Constitutional impregnation,” or “conservative 
adaptation,” is the organic result of persistence in a given direction under 
similar conditions. (5) Variations due to environmental influence are 
certainly transmissible, and may modify the organism so as to originate 
new species without the help of natural selection. (6) Use and disuse 
may similarly condition new characters, which persist without natural 
selection. The latter has only a subordinate role ; growth and the 
environment explain almost all. 
“ Variations occur throughout in perfectly definite, and only in a few 
directions, and are due to physico-chemical conditions in the interaction 
between the material composition of the body and external influences.” 
“ In my opinion, the physical and chemical changes which 
the organism experiences during its life, through the influence of the 
environment, and which it transmits, are the first conditions of modifica- 
tion, and of the origin of species. From the material thus supplied, the 
struggle for existence may select.” All variations express themselves 
simply as growth, and that in different directions. “Just because the 
organic modification depends upon physico-chemical processes, the result, 
as in the inorganic crystal, is defiuite.” “Varieties and species are 
essentially nothing but groups of forms which have remained at various 
stages of a progressive development.” Emphasis is laid on this stoppage 
of forms ( Genepistasis ) at various levels. Six factors are taken in account : 
(1) Direct external influence; (2) strengthening through function, or 
the reverse from disuse ; (3) struggle for existence, an indirect influ- 
ence ; (4) saltatory development, or sudden variations arising as the 
