A HUMAN EMBRYO WITH SEVEN PAIRS OF SOMITES 
MEASURING ABOUT 2 MM, IN LENGTH. 
BY 
WALTER E. DANDY. 
From the Anatomical Laboratory, Johns Hopkins University. 
WITH 6 PLATES. 
Among the youngest human embryos and one of the youngest in 
Professor Mall’s collection, is Embryo No. 391, which he has very 
kindly permitted me to reconstruct and describe. In general devel- 
opment this embryo is almost identical with, probably a trifle older 
than, the Kroemer-Pfannestiel embryo, Klb, which measures 1.8 
mm. and has six pairs of somites. It is older than Eternod’s 
embryo measuring 1.3 mm., Graf Spee’s Gle 1.54 mm., and Embryo 
Frassi 1.17 mm., in the order named. It is younger than the 
embryos of Unger and Bulle, of 9 and 14 somites respectively, 
Eternod’s 2.1 mm. embryo, and embryos XLIV (Bff), LX VIII (Lg. 
2.15 mm.), VI (B. R. 2.2 mm.) and VII (E 2.1 mm.) of His. 
This very rare specimen came into Professor Mall’s possession 
through the kindness of Dr. R. W. Pearce, of Albany, New York, 
with the following history from the physician who handed the speci- 
men to him. “The woman had passed her period about two weeks 
when she performed an abortion with a stick about 8 inches long, 
which she whittled out for the purpose. This she passed into the 
uterus and 24 hours later this specimen was aborted. Her purpose 
in calling me was to see if her object had been attained. I have 
kept the specimen two years in a bottle of weak formaldehyde.” 
Upon receipt the following measurements were made by Professor 
Mall; ovum 16x14x12 mm., embryo about 2 mm. The specimen 
was placed in fresh formalin, stained with alum-cochineal-eosin, 
imbedded in paraffin and cut into serial sections 10 microns in 
thickness. 
From these sections (163 in number, excluding the bauchstiel), 
the embryo was reconstructed upon a scale of 200 magnification, 
THE AMERICAN JOURNAL OF ANATOMY.—VOL. 10, No. 1, JAN., 1910. 
