DEPARTMENT OF EXPERIMENTAL EVOLUTION AND 

 EUGENICS RECORD OFFICE.^ 



C. B. Davenport, Director. 



The present seems a fitting time to look back over the past work of 

 the two departments reported upon herewith and to consider the plans 

 for the future. 



The Station for Experimental Evolution was started in 1904, not 

 long after the beginning of the new era, which dates from the redis- 

 covery of Mendel's law by De Vries, Correns, and von Tschermak in 

 1900. That our highest hopes for the Station have all been realized can 

 not be affirmed; but in some respects we builded better than we knew. 

 Thus at this Station was made the first discovery of the variation of 

 chromosomes associated with, and inducing, a corresponding mutation 

 of a species (the evening primrose) . This lead has opened up great ad- 

 vances made by Professor Morgan and his colleagues. By discoveries 

 made at this Station we see clearly that there are two types of muta- 

 tions — the one due to irregularities of assortment of chromosomes and 

 the other to changes in the chromosomes themselves; there are inter- 

 chromosomal mutations and intrachromosomal mutations. 



Again, studies made at this Station on the evolution of the chromo- 

 somal complex, especially in the flies, have led to the general concep- 

 tion that evolution has proceeded not primarily by modifications of the 

 series of visible organisms whose evolution is the goal of our researches, 

 but rather evolution has proceeded by changes in the ''germ-plasm," 

 the chromosomes, and that these changes have occm-red in some cases 

 apparently owing to its intrinsic properties — ^as radium changes into 

 lead — and sometimes under the influence of intracellular changes, such 

 as are induced by hybridization, and sometimes, perhaps, by extreme 

 conditions external to the germ-cell. However it arises, once a change in 

 the germ-plasm occurs, a coiTesponding change occurs in the body that 

 develops under the control of that changed germ-plasm. The "giant 

 evening primrose" is a giant just because it has, by a sort of accident, 

 gained additional chromosomes. The polydactyl fowl, or man, has 

 this peculiar condition because, in advance, a corresponding change in 

 the " genes "of the chromosomes has occurred. Man is tailless, we may 

 guess, because of a change in the gene that permits or induces a tail to 

 develop. If that change had not occurred, man would doubtless have 

 been a tailed "thinking being. " Mankind is what it is in its physical, 

 mental, and temperamental aspects because of the antecedent changes 

 that occmTed in the chromosomes of man's ancestors; and even inside 

 of the "human" group, by changes in genes, numerous inheritable sub- 

 groups or "biotypes" have arisen with their physical, mental, and tem- 



^Situated at Cold Spring Harbor, Long Island, New York. 



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