SHORTER ARTICLES AND DISCUSSION 



ON SELECTIVE PARTIAL STERILITY AS AN EXPLA- 

 NATION OF THE BEHAVIOR OF THE DOUBLE- 

 THROWING STOCK AND THE PETUNIA 



My attention has only just been drawn to the paper by Howard 

 B. Frost 1 which appeared in the issue of the American Nat- 

 uralist for October, 1915, under the title of ' ' The Inheritance of 

 Doubleness in Matthiola and Petunia," In this paper, which is 

 a preliminary communication, the writer states that from a con- 

 sideration of the data contained in the accounts which I have 

 published of my experiments on the cross-breeding of pure single 

 and double-throwing strains of stocks (Matthiola), he has been 

 led to form a view differing from that which I have put forward 

 as to the interpretation to be placed upon these results. Ac- 

 cepting the essential points requiring explanation to be as I have 

 stated them, he discusses the scheme which I have suggested as 

 underlying and accounting for the facts observed, and also the 

 explanation of these facts proposed by G-oldschmidt. 2 Though 

 conceding that the factorial scheme which I have formulated 3 

 would give the results observed, he rejects it on the ground that 

 it is unnecessarily complex, and claims that his own interpreta- 

 tion, which he then gives, is both simpler and supported by defi- 

 nite evidence. Though it is evident that a final decision on the 

 points raised must await further investigation, we can in the 

 meantime examine in the light of our present knowledge the two 

 main grounds upon which Frost claims that his explanation is 

 to be preferred, viz., (1) its greater simplicity and (2) the ex- 

 istence of definite evidence in its favor. 



For the purposes of this comparison we need take into account 

 only the three following outstanding facts : 



1. That whereas some single stocks yield only singles in each 

 successive generation other strains yield a mixture of singles and 



