242 WALTER S. SUTTON. 



cases, there are many different expressions of each character (/. c., 

 many different allelomorphs as suggested by Bateson 3 in regard 

 to human stature), which on various combinations would neces- 

 sarily exhibit relative dominance. The experiments with peas 

 show an almost constant dominance of certain allelomorphs, 

 such as round over wrinkled in seeds, and of yellow over green 

 in cotyledons ; but it is worthy of note that here, as in most Men- 

 delian experiments, only two antagonistic characters have been 

 used. Investigations on varieties, in general similar, but exhibit- 

 ing different expressions of some particular character, will cer- 

 tainly yield instructive results. Bateson's observations on crosses 

 between single-, rose- and pea-combed fowls, represent a simple 

 form of such a case and may be expected on completion to add 

 much to our knowlege of the nature of dominance. 



In addition to the many examples brought forward by Bate- 

 son in support of the Mendelian principle he cites three types of 

 cases which are to be regarded as non-Mendelian. These are : 



1 . The ordinary blended inheritance of continuous variation. 



2. Cases in which the form resulting from the first cross breeds 

 true. 



3. The " false hybrids " of Millardet. 



i . Blended Inheritance. In treating of this class Bateson 

 clearly states the possibility that the case may be one entirely 

 "apart from those to which Mendel's principles apply," but goes 

 on to show how it may possibly be brought into relation with true 

 Mendelian cases. He says in part : " It must be recognized that 

 in, for example, the stature of a civilized race of man, a typically 

 continuous character, there must certainly be on any hypothesis 

 more than one pair of possible allelomorphs. There may be 

 many such pairs, but we have no certainty that the number of 

 such pairs and consequently of the different kinds of gametes are 

 altogether unlimited, even in regard to stature. If there were 

 even so few as, say, four or five pairs of possible allelomorphs, the 

 various homo- and heterozygous combinations might, on sed- 

 ation, give so near an approach to a continuous curve that the 

 purity of the elements would be unsuspected, and their detection 

 practically impossible." This hypothesis, which presents no 

 difficulties from the point of view of the chromosome theory, is 



