9 
Warren Harmon Lewis 413 
part of the sphincter anlage. Fig. 9 shows an epithelial bud (Sph”) 
which I believe would have soon broken away from the pigment layer to 
form the lateral portion of the sphincter anlage. The pigment stops ab- 
ruptly in the pedicle and the 
enlarged end of the bud is 
entirely free from pigment 
and similar in appearance 
to the sphincter bud (Sph) 
derived from the pupillary 
margin of the optic cup. In 
this eye there were many 
such buds as Sph”, and as 
in the chick 8 days and 12 
hours old, arise about the 
same distance from the 
s Spee Fig. 9. From a chick 10 days, 9 hours old. Mag. 130 
pupulary margin, and the gia. Sph.’, sphincter bud from pigment layer. 
greater number of them 
are opposite the ciliary processes. Fig. 10 is a diagram showing the dis- 
tribution of these buds over one-half of the iris. There were thirty on 
this half of the iris arising at about the same distance from the pupillary 
Fie. 10. Diagram of the position of the sphincter buds arising from the pigment 
layer over one-half the iris in a chick 10 days, 9 hours old. Mag. 30 dia. Amn., angle 
of anterior chamber; P., pupillary margin. 
margin. Figs. 11, 12 and 13 show similar buds in a chick 13 days old. 
The buds are arranged in two series, as will be seen in the diagram 
(Fig. 14). The more lateral series (Sph”) are the most numerous. The 
pedicles of many of the buds have disappeared, leaving the free epithelial 
masses in the stroma of the iris as Sph”, Fig. 12, and Sph’, Fig. 13, 
The detached masses and buds are free from pigment except the basal por- 
tion of the pedicle and for an occasional granule or so in enlarged end. In 
all of these buds and free masses the staining reaction and the nuclei are 
