160 



Table I. 



Bursa bp. simplex (abC) X Bursa H. heteris (ÄBc) 



Ped. No. 056.64 



Ped. No. 059. 



T 



Bursa bp. heteris {ABC) 



Ped. No. 0564.88 

 Ped. No. 059.89 



Bursa-pastoris Series (C) 



Heegeri Series (c) 



Ped. No. 



06196 

 06197 

 06212 



Total 

 Expected 



1447 

 1368 



401 : 469 : 112 

 456 : 456 : 152 



69 

 63 



19 

 21 



21 

 21 



21.9 : 1 

 3.0:1 



The deficiencies seen to be consistently present in all these 

 pedigrees in the number of rhomboidea and simplex were pro- 

 bably due at least in part to an error of Classification, those rhom- 

 boideas having the greatest elongation of the terminal Segment 

 of the lobes having doubtless permitted their Classification as 

 minns-fluctuations of heteris, and the sharpest-lobed simplex as- 

 minus-fhictuations of tenuis. The greatest surprise was occasioned 

 by a ratio of about 22 : 1 in the form of the capsules, as it was 

 thought probable that the difference between the two forms 

 would be found to be dependent upon the presence and absence 

 of a single gene, the expected ratio on this assumption being 3:1. 



At the close of the second generation the cultures were 

 necessarily discontinued, and could not be resumed until in the 

 autumn of 1910. The appearance of a paper by Nilsson-Ehle % 

 showing that certain characters of wheat and oats are independ- 

 ently determined by two or more distinct nnits or genes, gave 

 the Suggestion that the capsule-character of B. bursa-pastoris 

 might be determined in like manner by two genes, the absence 

 of both of which produces the Heegeri-tyipe of capsule, although the 

 observed ratio 22 : 1 is a bad approximation to the expected ratio 



J ) Nilsson-Ehle, H., Kreuzungsuntersuchungen an Hafer und Weizen., 

 pp. 122. 1909. Lund: Hakan Ohlssons Buchdruckerei. 



