WANDERING PIGMENTED CELLS ARISING FROM THE 
EPITHELIUM OF THE OPTIC CUP, WITH OBSERVA- 
TIONS ON THE ORIGIN OF THE M. SPHINCTER PUPIL- 
LAE IN THE CHICK. 
BY 
WARREN HARMON LEWIS. 
Associate in Anatomy, Johns Hopkins University. 
Wi1TH 1 TABLE AND 15 TEXT FIGURES. 
INTRODUCTION. 
Nussbaum’s* important discoveries of the origin of the M. sphincter 
pupillae in birds and mammals from the epithelium at the pupillary 
margin of the optic cup and of the origin of the retractor lentis muscle 
in fishes from the epithelium bordering on the choroid fissure are of 
deep significance. His discoveries have recently been confirmed by 
Szili,” who has traced carefully the development of the sphincter pupillae 
muscle in man from the epithelium about the pupillary margin of the 
optic cup. Herzog* has also found a similar origin in a series of verte- 
brates. These authors have also studied the development of the dilator 
pupillae from the epithelial cells of the outer layer of the optic cup. 
| The origin of the retractor lentis, the muscle of accommodation in fishes 
(Salmo salar), lead Professor Nussbaum to suspect that the ciliary 
muscle, the muscle of accommodation in higher vertebrates, might also 
be of epithelial origin. With this in view I attempted at the suggestion 
of Professor Nussbaum to determine if the ciliary muscle in the chick 
was of epithelial origin. It is a pleasure to express my thanks to Pro- 
1Nussbaum: Die Entwicklung der Binnenmuskeln des Auges der Wirbelthiere. 
Archiv f. mik. Anat. u. Entwick. Bd. LVIII, 1901. 
Entwicklungsgeschichte des menschlichen Auges. Graefe-Saemisch. 2. 
FMI MS ANE Ve7o15 IN 
2Szili: Zur Anatomie und Entwicklungsgeschichte der hinteren Irisschichten, mit 
| besonderer Beriicksichtigung des'Musculus Sphincter Pupillae des Menschen. 
Anat. Anz., Bd. XX, 1901. 
Beitrag zur Kenntniss der Anatomie und Entwicklungsgeschichte der hin- 
teren Irisschichten, etc. v. Graefe’s Archiy fiir Ophthalmologie, Bd. LIII, 
1902. 
3Herzog: Ueber die Entwicklung der Binnenmuskulatur des Auges. Archiv fiir 
mikroskopische Anatomie und Entwick. Bd. LX, 1902. 
