July 12, 1&07] 



SCIENCE 



51 



Amphimixis occurs when variations origi- 

 nated under conditions of narrow breeding 

 are brought again into more normal relations 

 of broad-breeding, or into renewed contact 

 with the unrestricted descent of the species at 

 large. Mutative variations are often obliter- 

 ated by cross-breeding, and replaced by the 

 'normal characteristics of the wild type. 

 Amphimixis means that narrow varietal 

 strands can be retracted and reincorporated 

 into the specific network. 



Symbasis is the free interbreeding of the 

 normally diverse members of a species, which 

 brings about the coherent evolutionary 

 progress of the whole network of descent. 

 Symbasis keeps the procession moving, while 

 amphimixis rescues the strag^ers from the 

 side-paths. Amphimixis corrects abnormal 

 diversity induced by narrow breeding, but does 

 not interfere with normal diversity, nor with 

 evolution, and only appears to do so when the 

 degenerative mutations of narrow-bred organ- 

 isms are looked upon as genuine examples of 

 evolution. 



The static assumption is that the species 

 remains uniform and stationary until acted 

 upon by some agency which is external, or at 

 least intermittent. This was a very natural 

 assumption to make in the early days of 

 evolution because it involved the least pos- 

 sible modification of the earlier theory that 

 each species was the product of a definite 

 creative act. Under the static theory the 

 species could still be held to be ideally uni- 

 form. Evolution could be charged to the 

 environment, which was known to be able to 

 influence the development of individual 

 organisms, and could therefore be thought of 

 as influencing whole species. This idea of 

 definitely directed variation has been called 

 mutation by Waagen and orthogenesis by 

 Eimer. The formation of new species by dis- 

 continuous or saltatory variations has also 

 been called mutation by de Vries. 



All these conceptions are static, like the 

 Darwinian theory of natural selection. They 

 do not permit us to pass beyond the barrier of 

 ideal uniformity and stability, and forbid us 

 to find causes of evolution in anything except 



environmental influences. Dr. Ortmann's rea- 

 soning on the immanence of environmental 

 causes appears to be entirely logical, but it 

 can convince only those who disregard the 

 facts of nature and accept the static assump- 

 tion as the basis of inference. 



The second alternative conception of evolu- 

 tion was that of Naegeli, who believed that 

 evolutionary causes might reside in the proto- 

 plasm itself, and who worked out a theory of 

 protoplasmic structure which would provide 

 for systems of changes in definite directions. 

 This excited the ' hereditary mechanism ' 

 speculations of Weismann and his successors, 

 which continue to the present day, though it 

 has been usual to invoke environmental causes 

 to change the workings of the ' hereditary 

 mechanisms ' and to cause them to yield new 

 forms, which are supposed to be preserved by 

 selective or other isolation. 



The kinetic theory difPers from its predeces- 

 sors in recognizing that evolution is neither 

 initiated nor actuated by the environment. 

 Variations appear without environmental 

 causation and are preserved and accumulated 

 in the species by prepotency, instead of by 

 isolation. Isolation and narrow breeding 

 bring the degeneration which amphimixis 

 cures, but inside the normal network of de- 

 scent individuals are diverse and new varia- 

 tions are prepotent. Symbasis weaves the 

 diversities and the new characters together in 

 endlessly varying proportions, and in this way 

 conducts a constructive, coherent evolution, a 

 gradual advance of the whole network of de- 

 scent of the species. 



Such evolution Dr. Ortmann declares to be 

 incomprehensible, and so it may appear from 

 his static point of view. But the difiiculty 

 can be surmounted if he will take the italics 

 out of his ipse dixit of uniformity and allow 

 himself to become acquainted with the phe- 

 nomena of heterism, the contemporaneous 

 non-environmental differences which every- 

 where exist among the members of species, 

 and even among the simultaneous offspring 

 of the same parents. The normal diversity 

 and free interbreeding by which evolutionary 

 motion can be accomplished are concrete and 



