50 Mr Bateson, Note on the Resolution of 



Note on the Resolution of Compound Characters by Cross- 

 breeding. By W. Bateson, M.A., F.R.S., St John's College. 



[Bead 24: November 1902.] 



In the recently-published part of his Mutationstheorie (Lief, 

 iv. pp. 194 — 206), Professor de Vries records evidence of a valuable 

 kind respecting certain cases of resolution of compound characters, 

 and offers an interpretation of the phenomena. On consideration 

 it seems doubtful whether this interpretation is not unnecessarily 

 complicated, and it is the object of the present note to suggest 

 a simpler account. 



It will be remembered that in a case of simple Mendelian 

 inheritance the offspring of heterozygotes, AB, self-fertilised or 

 bred inter se, consist of only three forms, viz. the two homozygous 

 forms A A and BB, representing the pure parental types, and one 

 heterozygous form AB repeating that of the first cross. In such 

 a case we recognize that this result is due to the fact that the 

 gametes of A B are each bearers of either the A or the B character 

 in its entirety. In the constitution of these gametes the characters 

 A and B are alternative or allelomorphic to each other. 



But already many examples are known in which when two 

 pure forms A and B are crossed, the gametes of the AB's are 

 bearers not simply of characters A and B, but of a number of new 

 characters formed, as we may conceive it, by the resolution of the 

 compound character of one (perhaps both) of the original pure 

 forms. Until lately we had no evidence as to the statistical rela- 

 tions of the several gametes in such a case of resolution. By the 

 work of de Vries and of Tschermak 1 we are provided with some 

 materials for calculating these relations. From the distribution of 

 characters among the offspring in these cases, and from the 

 statistical relations of the several zygotic forms to each other, it 

 is clear that the resolution and redistribution of characters may 

 take place in several different methods, but until the facts of the 

 next generation (grand-children of the hybrid) shall have been 



1 Tschermak, Ueber die gesetzniassige Gestaltungsiveise der Mischlinge, Ztschr. 

 landw, Versuchswesen in Oesterr., 1902, Tab. n. — v. 



