60 DAVENPORT— DETERMINATION OF DOMINANCE [April 25, 



dence of this sort could be adduced proving the insufficiency of the 

 theory of the recessive nature of novelties. A different theory has 

 been suggested by deVries, namely, when an individual having the 

 characteristic patent is crossed with one in which it is latent the 

 patent characteristic is dominant, the latent recessive. A similar 

 expression has been proposed by Hurst who concludes that the pres- 

 ence of a quality usually dominates over its absence. This expres- 

 sion of the facts is, in the main, true but it is too narrow, inas- 

 much as it assures that the mendelian result occurs only when a 

 character is crossed with its absence ; but this I shall show directly 

 is by no means true. 



Two years ago I suggested that a progressive variation, one 

 which means a further stage in ontogeny, will dominate over a con- 

 dition due to an abbreviation of the ontogenetic process — or a condi- 

 tion less highly developed than the first. Recent studies have thrown 



Fig. I. 



additional light on this matter and I wish to treat it now generally. 

 First let me present some illustrations. Many poultry have feathers 

 on the feet; these constitute the so-called boot. If a "booted" bird 

 be mated with a non-booted all offspring are booted — booting is 

 dominant over its absence. Booting occurs, however, in an infinity 

 of grades. For convenience I recognize ten, usually determined by 

 inspection. If a bird with a boot of grade 8 or 9 be crossed with a 

 bird with boot of grade 2 or 3, both being pure dominants, then the 

 stronger condition is dominant in the offspring, so that their average 

 grade is about 8. 



A second illustration may be drawn from certain studies made 

 on the asparagus beetle by Dr. F. E. Lutz, of the Carnegie Insti- 

 tution of Washington. In the embryonic condition the outer wing 

 covers of this beetle are nearly pigmentless or yellow. Before 



