396 MALL. Vion.) excl: 
TABLE OF YOUNG HUMAN OVA. 

TIME BETWEEN 
DIAMETER OF First LAPSED 
OBSERVER. Empryonic Vesicuz, | DIAMETER OF OVUM. | “periop AND 
ABORTION. 
Malls(No. XI), 23%: Tes OG mm. TOL 2X 72min 13 days 
ReICHEKt - mies seine oa I.75X1.5 se SoS ISSA se TAs 
Von Spee (v.H.) . . 1.84X 1.083 “ Gs X, 1455), 5° tap 
Von Spee (Gle.) . Za es2s ce TOs eTRO.G <6 T2 mus 
Mall (No. XVI). 251) G21 ce iin eSetsy 1 13) uss 
His (Lg.) .- 2.15X2 ‘s HS. oh. Gece T2hianes 
Von Spee . 2.69 X 3 sé WSs 14 ‘ WAM as 
Janosik . 3. x4 - 8. ee ost 



* These are all of the authentic young human ova I can collect from the litera- 
ture giving all of their measurements as well as the menstrual history of the mother. 
In both of von Spee’s cases the time between the abortion and the end of the last 
period is given; in embryo v. H. the time is given as “exactly five weeks,” while 
in embryo Gle. “five weeks ” is given. If we estimate the duration of menstruation 
as five days and its frequency twenty-eight days, then the time between the first 
lapsed period and the abortion is twelve days, as I have given it in the table. 
ing the specimen. Just at this time the growth of the chorion 
is precocious, as is also the case in the dog,! rabbit,? and 
monkey. 
The papers by Bischoff and by Selenka are worthy of the 
most careful study by every embryologist, and I take the liberty 
of rearranging some of Bischoff’s data on the development of 
the dog. His observations are very extensive, and give us the 
basis for our present ideas of the passage of the ovum into the 
uterine tube after fertilization. Unfortunately, they were 
made before the time of sectioning specimens, yet they are 
more complete than most researches relating to this subject 
published since his time. 
The portion I tabulate relates to the size of the embryonic 
mass or vesicle, the size of the ovum, and its approximate age. 
As far as I have been able to determine, these data taken from 
the dog are still the most important ones with which we can 
1 Bischoff: Entwicklungsgeschichte des Hundes Eies, Braunschweig, 1845. 
2 Bischoff: Entwicklungsgeschichte des Kaninchen Eies, Braunschweig, 1842. 
3 Selenka: Studien iiber Entwicklungsgeschichte des Thiere, Heft 5, Wies- 
baden, 1892. 

