September 9, 1921] 



SCIENCE 



213 



be the quality of life that does not contravene 

 them. The social sciences of ethics, education, 

 economics, politics and government will be- 

 come what they never have been — genuine 

 sciences; fashioned by a just conception of 

 man, they will cooperate to fashion the state; 

 and the state, which may ultimately embrace 

 the world, will rescue itself from ignorant 

 iwliticians and commit its destiny to the 

 guidance of holiest men who Jcnow. 



And when guided by honest men who 

 know — when guided, that is, by the coming 

 .science of human engineering, which will be 

 intelligence applied to human affairs — when 

 thus guided in the light of the true conception 

 of man as the binder of time — then and only 

 then our human civilization — the living issue 

 of time-binding toil, mainly that of the dead — 

 will advance, not haltingly as hitherto, but, 

 as said, in accord with the natural law thereof, 

 in a warless world, swiftly and endlessly. 



Cassius J. Keyser 



Columbia University 



MENDELIAN OR NON-MENDELIAN? 



In 1907, several years after the Mendelian 

 discoveries had begun to attract general inter- 

 est, a writer endeavored to limit " Mendelian 

 heredity " to the occurrence of 3 to 1 pheno- 

 typic ratios. All other ratios were held to 

 represent other systems of inheritance. This 

 extreme view was not held by any one actually 

 engaged at that time in genetical investi- 

 gations, and the paper referred to was en- 

 tirely ignored by geneticists because its author 

 was so obviously ignorant of the real impli- 

 cations of the Mendelian discoveries. 



Recently, two of our foremost geneticists^ 

 have gone to the opposite extreme in stating 

 what should be included in Mendelian hered- 

 ity, declaring that " Mendelian heredity has 

 proved to be the heredity of sexual reproduc- 

 tion; the heredity of sexual reproduction is 

 Mendelian." Certainly few geneticists would 

 at the present time include so much under 



1 East, E. M., and Jones, D. F., "Inbreeding 

 and Outbreeding." 285 pp. Philadelphia: J. B. 

 Lippineott Co., 1919. See p. 50. 



the term " Mendelian heredity," though one,- 

 at least, there is, who sympathizes with this 

 dictum. 



Between these extreme views as to the 

 meaning to be attached to the expression 

 " Mendelian heredity " different geneticists 

 have taken different positions and even one 

 and the same writer has given the term 

 different meanings at different times. These 

 differences of usage have led to misunder- 

 standings and to some controversy. 



Davis^ has placed the mere occurrence of 

 segregation in the CEnotheras equivalent to 

 Mendelian inheritance, thus accepting the 

 validity of a criticism made by East* based 

 on the same conception as that quoted above 

 from East and Jones, that all heredity in 

 sexual reproduction is Mendelian. As I under- 

 stand it, however, the occurrence or non-occur- 

 rence of segregation in the CEnotheras has 

 never been an important issue; the real 

 question has been whether the segregation 

 which does quite obviously occur is of the 

 Mendelian type, i.e., whether the hereditary 

 factors are distributed during gametogenesis 

 and fertilization according to the formulation 

 actually developed by Mendel in interpreting 

 the results of his experiments. 



Other writers^ have grouped the phenomena 

 of segregation under the terms " Mendelism " 

 and " neo-Mendelism," but include under the 

 latter name several phenomena which are now 

 generally recognized among geneticists as 

 differing in no essential way from the actual 

 cases studied by Mendel. Still others speak 

 of " orthodox " Mendelism, implying that 

 there is also a " heterodox " Mendelism, or 

 they use the expressions " strictly Mendelian," 



2 Wright, S., ' ' Systems of mating. I. The 

 biometric relations between parent and offspring." 

 Genetics, 6: 111-123. 1921. See p. 111. 



3 Davis, B. M., ' ' Hybrids of CEnotliera iiennis 

 and CEnotliera franciscana in the first and second 

 generations," Genetics, 1: 197-251. 1916. 



•* East, E. M., ' ' The Mendelian notation as a 

 defcription of physiological facts," Amer. Nat., 

 46: 633-655. 1912. 



5 Coulter, J. M., and Coulter, Merle C, ' ' Plant 

 Genetics. " ix -|- 214 pp. Chicago : Univ. of Chi- 

 cago Press. 1918. See pp. 40-96. 



