all the radii converge upon the study of the factors and 

 method of species transformation. 



We can only mention some of the modern departments 

 which have yielded brilliant results, such as cytology, ex- 

 perimental embryology, experimental fertilization, and 

 regeneration. But we may point out that the general 

 problems in these various fields deal like the problem of 

 evolution itself with an analysis of the internal and ex- 

 ternal influences that determine the final adult conditions 

 of species. For example, the adult salamander possesses a 

 specific structure, in a state of balance or adaptation, that 

 is the final result of an evolution process up to the present 

 time ; this same specific condition is the goal of the changes 

 through which the salamander's egg and embryo pass in 

 development; it is the goal also that may be reached by 

 even a portion of a divided salamander's egg; while finally 

 it is the goal of the regenerative processes that enable a 

 salamander from which a leg has been cut off to reproduce 

 the missing part. Everything centers then about the ques- 

 tion as to the origin of adult specific forms, which exhibit 

 adaptation. 



Realizing this, we may pass on immediately to consider 

 how through the study of adaptation, Darwin was led to 

 formulate his potent theories, which have been the basis for 

 recent progress. As the other speakers upon biological 

 sciences have already stated, the most striking feature of 

 animals and plants is their adjustment to their vital condi- 

 tions. An organism that seems so sufficient unto itself, so 

 capable and independent, is nevertheless inextricably in- 

 terlocked with its surroundings, for its very substance is 

 composed of materials which with their endowments of 

 energy have been wrested from the environment. An 

 animal that is pressed upon by the substances of the outer 

 world, that is played upon by various energies, and is 

 attacked on all sides by innumerable foes, finds itself in- 



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