[ 399 ] 



XXVII. 



UNSOUND MENDELIAN DEVELOPMENTS, ESPECIALLY AS 

 REQAEDS THE PRESENCE AND ABSENCE THEORY. 



By JAMES WILSON, M.A., B.Sc, 

 Professor of Agriculture in the Eoyal College of Science, Dublin. 



[Read November 26 ; Piiblislied December 18, 1912.] 



In this paper it is proposed to show — 



i. That the Presence and Absence theory is unsound, 

 ii. That it leads to erroneous conclusions. 



iii. That phenomena to which it has been applied can be analysed by 

 ordinary Mendelian formulae. 



To do this it will be necessary first of all to state some part of the 

 Mendelian position, and to show how formulee are used in analysis. It is 

 that there are factors or determinants for every character. The characters 

 of similar parents may be represented thus : — 



Male. Femaib. 



>w pqr 



The factors which such parents produce to be handed on to their 

 progeny may be represented thus : — 



Male. Female. 



PCIENT. PROG. K.D.S., VOL. XIII., NO. XX\ai, 3 



