246 WALTER S. SUTTON. 



Saunders found in Datura or as Tchermak's pied yellow and green 

 peas obtained by crossing the Telephone pea with yellow varie- 

 ties. Correns describes the condition as pcecilodynamous and his 

 conception of the causes of the phenomenon as I understand it 

 is parallel with that which I ha\e outlined above. The logical 

 possibility suggested by Bateson ' that the recessive islands in 

 such cases as the mosaic pea may be clue to recessive allelo- 

 morphs in the paired state does not accord with the theory of a 

 chromosomic basis for those allelomorphs, since the chromo- 

 some groups, both of cells showing the recessive character and 

 of neighboring cells showing the dominant one, are derived, so 

 far as we know, by longitudinal or equation division from the 

 chromosomes of the same original cleavage nucleus and hence 

 must be alike. 



The application of the theory here suggested may be put to 

 test by an experiment in which hybrids of dissimilar true-breed- 

 ing parentage are crossed and a third generation of " quarter- 

 bloods " produced. Mosaics occurring in such an organism, if 

 this theory be correct, would show one character resembling that 

 of one of the maternal grandparents and one resembling that of 

 one of the original pure-breds of the paternal side. If both 

 characters of the mosaic should be clearly paternal or maternal 

 the theory as outlined is proven inadequate, since one of each 

 pair of chromosomes, and hence the corresponding character- 

 group, is thrown out by the reduction-division in each generation. 



'In considering the behavior of the two chromosomes forming 

 the basis of any given character, it was noted that in some cases 

 the heterozygote character resulting from the combinations of 

 dissimilar allelomorphs is sometimes totally unlike either of the 

 latter. Thus Mendel found that in crosses between peas respec- 

 tively I and 6 feet in height the offspring ranged from 6 to 7^ 

 feet. In discussing similar cases, Bateson calls attention to the 

 light which would be thrown on the phenomenon if we ventured 

 to assume that the bases of the two allelomorphs concerned are 

 chemical compounds ; and he compares the behavior of the allelo- 

 morphs to the reaction of sodium and chlorine in the formation 



1 Bate- on and Saunders, p. 156. 



