410 
did not find epithelial buds lateral to the ciliary region. 
Wandering Cells and Muscles from the Optic Cup Epithelium 
The buds we 
have so far considered have contained several cells and nuclei, occasion- 
ally the buds may consist of but a single cell as seen in Fig. 6. 
Fie. 5. Froma chick 8 days, 12 hoursold. Mag. 
130 dia. Ac., anterior chamber. 
An examination of the table 
will show that the pigment be- 
gins to appear in the pigment 
layer during the fifth day, while 
only a few pigmented wander- 
ing cells were found as early as 
the eighth day (in the chick 
7 days and 22 hours old). If we 
assume that what I have called 
epithelial buds are merely pig- 
mented connective tissue cells 
sending processes into the pig- 
ment layer, we might expect to 
find pigmented wandering cells 
before pigment began to appear 
in the pigment layer, but no such specimen was found; or again, we 
might expect to find numerous transition stages among the connective 
tissue cells with varying amounts of 
pigment from a few granules (of a 
yellowish color) to the heavily laden 
ones with dark granules. Such tran- 
sitions practically never occur in the 
same specimen. On the contrary the 
wandering cells appear to contain pig- 
ment of about the same color and den- 
sity, which corresponds closely to the 
condition of the pigment in the pig- 
ment layer. Where there is a differ- 
ence that of the wandering cells is 
generally a little darker than that in 
pigment layer as though the progres- 
sive changes from brown or yellow to 
black had gone on faster in the iso- 
— 
Fiac. 6. From a chick 11 days, 3 hours 
old. Mag. 550 dia. Showing epithelial 
bud of one cell from pigment layer. 
lated wandering cells than in the pigment layer. Again if the connective 
tissue cells were sending processes into the epithelial layer we would 
expect to find such pigmented wandering connective tissue cells in the 
stroma previous to their attachment to the epithelial layer, but in only 
one specimen did I find the wandering pigmented cells without the pres- 
