t 
— 
1905. } HEREDITY IN PIGEONS. 55 
only on each foot, and it is more usual to find the development 
of the web nearly symmetrical in the two feet. 
It sometimes occurs between digits il. and ili. sometimes 
between il. and iv., and sometimes between all three. 
The instances in which it reaches the bases of the claws between 
all the digits on both feet are rarer. It has occurred on one foot 
only. 
Though this character has been observed to occur in the 
offspring of normal-footed parents, I have never heard of an 
instance in which all the young so bred were webbed. It has 
been found in a pigeon bred from parents of two different strains, 
and I have also heard of cases in which it occurred from time to 
time in the same strain, birds showing the character having 
been discarded. 
The general result of the experiments is that the inheritance 
of the webbed foot is Mendelian. 
It is recessive to the normal foot. 
The character is not a thoroughly satisfactory one to work 
with, as it is hable to considerable fluctuation in extent. 
Extracted recessives, though all show webbing, have this 
character In various degrees; in some if reached only to the first 
interphalangeal joint of the second and third digits, or to the 
second joint of the fourth digit. 
On examining the normal population J find that birds ocea- 
sionally, though rarely, occur with webs as extensive as this. 
In the families here recorded I took the first interphalangeal 
jomt of the second and third digits and the second joint of the 
fourth digit as a minimum, and counted as “ webbed ” all birds 
with a web reaching this minimum in the case of at least two 
adjeining digits: all birds with less webbing than this being 
iven as normal. 
If a much greater series of numbers could be investigated, 
undoubtedly there would be overlapping between the two classes 
of normal and webbed birds. 
On the other hand, the evidence, so far as it goes, does not 
indicate that the degree of webbing in the parents closely limits 
the amount in the offspring, for moderately webbed birds have 
given birds more webbed, and fully webbed birds have given 
offspring less webbed (see exp. 13 and 14). 
I hope later to make further experiments with the lower states 
of this condition. 
Web-footed 3 wsed'in Experiments. 
The Pigeon which I used in the following experiments 
somewhat resembled an Antwerp in appearance, but was of no 
distinct variety. The web extended to the base of the claws in 
both feet, but the digits were rather closely webbed together 
except ill. and iv. of the right foot, where the web was sufficiently 
loose to allow the usual spread of the foot. The bird was of the 
Proc. Zoot. Soc.—1905, Vou. I. No. XXXVIT. 37 
