It is rare to obtain an embryo of small size that is well preserved. Such an opportunity was presented to me in the specimen to be described. Many interesting features of the early embryonic development of the eye were clearly seen in serial sections.
The embryo was obtained through Dr. M. A. Goldberger, of the department of gynecology at Mount Sinai Hospital. It was taken directly from the uterus at the time hysterectomy for fibroids was performed, thirty-two days after the onset of the last menstrual period. It therefore could not have been more than 3½ weeks old. It was immediately placed in 10 per cent solution of formaldehyde. With its membranes it measured 7 millimeters from end to end, but microscopic sections later indicated a development usually ascribed to the 5.5 mm. stage.1 This is probably the more accurate measurement.
The embryo was fixed in 10 per cent