T H E 
HEW PflYTOIiOGIST. 
Vol. VIII., No. 8. October, 1909, 
Published November 2nd. 
RECENT ADVANCES IN THE STUDY OF HEREDITY 
(A Course of Lectures, for the University of London, delivered in the 
Summer Term, 1909). 
By A. D. Darbishire. 
LECTURE IV. 
The Nature of the Allelomorphic Pair. 
X F it could be shewn that all the characters of organisms were 
represented in the germ-cells by material units or factors, 
which were associated in pairs in such a way that one was 
dominant to the other when they met in conjugation; and that 
these units segregate in the formation of the germ-cells, it might 
well be claimed that the key to the problem of heredity had been 
found. 
The phenomena presented by the inheritance of the characters 
of Pisum to which we have paid especial attention are in complete 
accord with the supposed state of affairs set forth in the preceding 
paragraph. The mode of inheritance of the characters of the coty¬ 
ledons of Pisum sativum is in close accord with the theory that 
the two characters, round and wrinkled for instance, are represented 
in the germ-cells by separately heritable entities; and we may 
fairly regard it as demonstrated that, when they meet in fertili 
zation, one of them is dominant to the other. 
If all the attributes of organisms could be analysed into uni 
characters, such as round and wrinkled, and their Mendelian 
behaviour in inheritance demonstrated, there is no problem in 
