( Ixxxix ) 



The results are summarised as follows : " In Drosophila there 

 occur minute changes in the germinal material, such as to 

 give, so far as our present imperfect knowledge goes, seven 

 diverse grades of a color which is itself only one grade of 

 another series of seven known grades. By means of these 

 graded changes one could obtain, by the mutationist's own 

 statement, the continuously graded results which selection 

 actually gives. What more can the selectionist ask? " 



As the author remarks in paper (2), " The work in Men- 

 delism, and particularly the work on Drosophila, is supplying 

 a complete foundation for evolution through the accumulation 

 by selection of minute gradations. We have got far away 

 from the old notion that hereditary changes consist only in 

 the dropping out of complete units, or that they are bound to 

 occur in large steps. . . . The objections raised by the muta- 

 tionists to gradual change through selection are breaking down 

 as a result of the thoroughness of the mutationists' own studies." 

 The importance of Mendelism as an aid to selection is 

 insisted on in the same paper. " Hereditary variations, such 

 as give rise to the multiple allelomorphs and multiple modify- 

 ing factors, occur in some organisnis rather infrequently, as 

 measured by the time scale of human happenings. If there 

 were no interchange of factors among individuals and stocks, 

 it would take a long time to obtain in one individual all the 

 six diluters of the eosin color of the Drosophila eye ; one 

 arises in one individual, another in another. But by selective 

 cross-breeding it is possible to bring together into one stock 

 all the modifiers that have been produced in diverse stocks. 

 Mendelism acts as a tremendous accelerator to the effectiveness 

 of selection." 



Keturning to paper (1), the author finally concludes that 

 " Evolution according to the typical Darwinian scheme, 

 through the occurrence of many small variations and their 

 guidance by natural selection, is perfectly consistent with 

 what experimental and palaeontological studies show us; to 

 me it appears more consistent with the data than does any 

 other theory." 



A VERY ANCiEXT Beetle. — The President exhibited a 

 specimen of a Carabid Beetle, Calosoma nigosum, de Geer, 



