BRACHYDACTYLY IN THE FOWL 107 
case of any individual embryo whether the observed condition 
is transient or definitive. 
The third degree is represented by one twenty day embryo 
and possibly one or two younger embryos. In this case there 
seems to be a general reduction in which the terminal phalanx 
suffers most. The third and fourth phalanges are fused. The 
claw is represented only by a small flat scale and the fifth bone 
Fig. 4 Feet of a brachydactyl embryo on the tenth day of incubation. In 
the fourth toe of the right foot, at B, is shown the completely fused third and 
fourth phalanges. In the left foot, at A, these two phalanges are seen to be 
only partially fused. 
by a little nodule into which the terminal slip of the flexor 
profundus tendon is inserted. Since the flexor profundus is 
also inserted into the plantar surface of the normal fourth 
phalanx or the fused third and fourth phalanges, a stage showing 
a complete absence of the fifth segment would differ very slightly 
from the case here described. It is interesting to note in this 
connection, however, that the basal and terminal phalanges are 
