114 REPORT OF THE CONFERENCE ON GENETICS. 
MENDELIAN CHARACTERS IN PLANTS AND ANIMALS. 
By C. C. Hurst, F.L.8., F.R.H.S. 
RecEnT experiments with many kinds of plants and animals have largely 
extended the application of Mendel’s law of heredity. 
In my own experiments and observations, for instance, the Mendelian 
principles have been evident in such widely different organisms as peas 
and rabbits, sweet peas and horses, tomatos and poultry, orchids and 
man. 
The main object of the experimenter has been to discover the 
Mendelian characters in each type of plant and animal by means of 
Mendel’s methods. 
In many cases this has been apparently easy, while in others it has 
been more difficult. 
In Mendel’s classical experiments with peas, the characters were patent, 
consisting simply of pairs of contrasts, e.g. round and wrinkled seeds, 
yellow and green cotyledons. Many similar cases have been found in 
other plants and in animals, and these usually follow the simple rules of 
dominance, segregation, and purity. 
In these simple cases the outward or zygotic character of a pure 
plant or animal is presumably represented in the germ-cells or gametes 
by a single factor or determiner. In other cases, however, the zygotic 
character, though apparently simple, is really compound, being represented 
in the gametes by more than one factor. 
Thus Mr. Bateson, Miss Saunders, and Mr. Punnett have recently 
demonstrated that red flower-colour in sweet peas and stocks is due to the 
association of two gametic factors, purple colour to three factors, while 
hoariness in stocks has been shown by them to be due to no less than 
four distinct gametic factors. 
These compound characters are not often to be detected at sight, and 
for the most part have to be subjected to a Mendelian analysis ere their 
true nature is discovered. 
What could appear more simple, for instance, than such characters as 
the red colour of the fruits of the ‘ Fireball’ tomato, the red colour of the 
flowers of the ‘ Crimson King’ Antirrhinum, the yellow-grey coat of the 
‘Belgian Hare’ rabbit, or the rose comb of the ‘Black Hamburgh’ 
fowl ? 
All these characters breed true to themselves, and have done so for 
many generations ; yet, as my experiments show, all are really compound 
characters, each being represented in the gametes by more than one 
factor. 
THE Rep Conour oF THE ‘FIREBALL’ Tomato, 
The ‘ Fireball’ tomato is a pure race, bearing red fruits: it has bred 
true to colour with me for at least ten generations. The shade of colour 
of the ripe fruits corresponds with that of ‘Rouge Tomate’ (Tomato 
