58 
AN EARLY HUMAN OVUM 
If the foregoing summary of the facts regarding these eleven ova 
be analysed, it will be found that the most precise data are supplied 
by the cases of Merttens, Beneke, Rossi Doria, Eternod, and Reichert. 
In the case of Merttens 16 days, in that of Beneke 20 days intervened 
between the end of last menstruation and operation; in the case of Rossi 
Doria 24 days elapsed between the beginning of the last period and the 
commencement of symptoms of abortion ; and in Eternod’s case the ovum 
was expelled 21 days after a single coitus. Eternod’s case supplies us 
with a fairly precise upper limit, on our method of estimating, and at 
the same time justifies us in excluding the possibility that in the first 
three cases fertilization occurred before menstruation. The case of Merttens 
may be taken as defining the maximum possible age of an ovum slightly 
older than that of Peters. The circumstances of Reichert’s case were very 
similar to those of our own ; fertilization in all probability occurred 
shortly before an expected period which was arrested. 
By utilising these data we can arrange the ova in a series in which 
dimensions and ages gradually increase. The results of the rule of His 
applied to these ova are brought out in the column in the table under the 
head of “ days elapsed from the omitted period.” It will be seen at once 
how contradictory the results are in the cases to which it can be applied, 
and it will be noticed that it is not applicable at all to five cases out of 
the twelve. This is of course due to the admitted error of three weeks 
under the rule. In dealing with these young ova it seems therefore 
necessary to proceed on the basis of some such “ normentafel ” as here 
given, and we submit our table as a tentative in that direction. That it 
is absolutely correct is not pretended, but that it is fairly correct in a relative 
sense is probable, because it is consistent in itself and with the data 
of comparative embryology. 1 
Having now obtained a chronological sequence in which the age is 
calculated from fertilization, a second table was constructed, to see at what 
periods of the month fertilization and imbedding would have taken place 
in these twelve ova, on the basis of the first table. The termination of 
pregnancy being known, the date of fertilization was arrived at by 
1 The table does not affect the ordinary obstetric reckoning, the basis of which is statistical. 
