Warren Harmon Lewis 409 
was the only bud found in the entire series of this eye and no wandering 
pigmented cells were found. In Fig. 4 the elongated epithelial bud 
consists of several cells with nuclei 
and pigment granules similar to 
those in the pigment layer. The 
loose pigment cells (Pe), seen in 
this figure, are evidently derivatives 
of this bud, their position, size, 
character of the nuclei, protoplasm 
and pigment granules all indicate 
this. The bud in this section is seen 
to arise from a definite place on the 
convex angle formed by the bending 
of the epithelial layers into the 
ciliary process. In this same eye Mag isbdia. P-C., wandering pigment cells, 
there are several other buds arising 
from similar locations at the angles where the epithelium bends into 
other ciliary processes. At some of these places there are detached 
masses of pigmented epithelium, the pedicles probably having just broken 
away and left the distal end of the bud in position, not sufficient time 
having elapsed for migration farther away from the pigment layer into 
the mesenchyme. There were no buds from more lateral portions of the 
pigment layer of the eye. From the iris portion of the pigment layer 
there were numerous buds for the most part free of pigment. They 
appear to take part in the formation of the lateral portion of the sphinc- 
ter muscle. These will be more carefully considered later. 
Fig. 5 from a chick 8 days and 12 hours old shows a large pigmented 
epithelial bud arising, in a position similar to that seen in figure 4, 
from the convex angle where the pigment layer bends into the ciliary 
process. There are a number of such buds in this eye with knob-like 
ends containing nuclei and pigment granules similar to those in the 
pigment layer. There are also detached masses of epithelial cells bearing 
the same relation to the ciliary processes as the knob-like ends of the 
attached buds. These loose masses are probably from buds whose pedi- 
cles have broken away. The anastomosing pigment cells are very 
numerous in the surrounding stroma. The pigment of many is a little 
darker than that in the pigment layer, but there are cells containing 
grades of colored granules like those in the pigment layer and others 
with intermediate shares. The general appearance of these cells, their 
nuclei and the staining of the protoplasm lead me to believe that most 
if not all of them are derived from the pigment layer. In this eye I 
28 
%, FT Tae Sere 
GeO Peo ae NIT, 
° a 84,09 0 
0191 
