2(i RADIOGENESIS IX EVOLUTION. 



a .set of universal laws. Karl Pearson/'' ('•. Archdall IJeidt 

 and others have pointed out that in certain denionstrabie 

 cases. Mendelian laws are contradicted or sujierseded, 

 anfl even the acceptance of what modern Mendelians call 

 '■ independent inheritance." does not solve the question. 

 Elsewhere, 1 have ventured to summarise my impres.sions 

 as follow : — ■ The supposed universality of the Meudelic 

 principle has been largely suggested by focu.ssing attention 

 on certain points and ignoring others. Heredity is more 

 often a complex synthesis than a mosaic of dominants 

 and reces.sives."i It must be adfled that several writers, 

 amongst whom may be noted E. C. Mac Do well,** have 

 endeavoured to interpret blended inheritance on Mendelian 

 lines 1)\- "" tnultijile factors." But whatever views are 

 ex])ressed as to the range of the Mendelian laws, there can 

 be no fjuestion that some of the most valuable work on 

 heredity during recent years has been the result of 

 investigators who have sought to establish this theory. 

 The accumulation of facts is of the utmost value, even 

 though theories which stimulated the workers who place 

 facts on record may have to be qualified. 



The majority of writers do not now dogmatise on the 

 ■ all-sufficiency " of natural selection. Even the query 

 as to the evolution of structure preceding the evolution of 

 function cannot always be answered in the affirmative. 

 Nowadays, it is not so much a case of putting the ^'iews 

 of Darwin again.st those of Lamarck, but of associating 

 the two, and laying the major stress on natural selection. 

 Instances are given of processes which cannot be wholly 

 explained by natural selection. Speaking on " By-products 

 of Evolution," Dendy,tt points out that natural selection 

 cannot be directly responsible for the minute differences 

 of the spicules of sponges, as these cannot be of importance 

 in the soft tissues of the sponge. Yet these minute spicules 

 exhibit constant specific characters. Possibly, they are 

 subject to an indirect control through being co-related to 



*" On a Generalized Theory of Alternative Inheritance, with special 

 reference to Mendel's Laws." (1904). 

 t '• Bedrock," Julv, 191:], ).. 232. 

 tPres. Address, Qld. Field Naturalist.^' ('lub, 1914. 

 **Jour. Exper. Zoology. Vol. XVI.. No. 2, i)p. 177-194, 1914. 

 TTPre~. Address. Quekett Microscopical Club, 1913. 



