372 Maximilian Herzog. 



Bryce and Teacher: 0.77, 0.63, 0.52 mm. 



Peters: 1.6, 0.9, 0.8 mm. 



Herzog: 2.326, 0.804, 1.204 mm. 



Graf von Spee: 2.5, 1.5 mm. 



Jung: 2.5, 2.2 mm. 



Mertens: 3.0, 2.0 mm. 



Beneke: 4.2, 2.2., 1.2 mm. 



Leopold: 4.0, 3.7 mm. 



Graf V. Spee: 4.0 mm. 



von Heukelom: 4.5, 5.5. 



Beigel-Loewe : 4.0, 5.0, 2.5-3.0 mm. 



It appears from the above table that the author's ovum is some- 

 what larger than Peters' ovum. However, the real difference in 

 the cubical contents of the two ova cannot be much, since the Ma- 

 nila ovum, while markedly larger in its longest diameter, is indeed 

 not strictly elliptical, like the Peters' ovum, but has the shape 

 of a biconvex lens. It is useless to speculate whether or not the 

 Manila and the Peters' ovum are of exactly the same age, or 

 whether the former is a little older than the latter. We have in 

 our case not made any efforts, at the time when the ovum was 

 obtained, to get data as to menstruation and probable time of con- 

 ception. Such an attempt would have been useless in the case of 

 a full-blooded native from the lower walks of life. Even in those 

 reported cases of very young ova, where these data were obtain- 

 able, the estimates as to the age of the embryo are not very cor- 

 rect. Peters estimated the age of his ovum as of three to four 

 days; Leopold, an older ovum (4.0; 3.7 mm), as seven to eight 

 days old. Jung thinks that the Peters' ovum is considerably older 

 than three to four days; Bryce and Teacher estimate its age at 

 thirteen to fourteen days. Von Spee and Minot believe that seven 

 to eight days intervene from the time of fertilization in the tube 

 till implantation occurs in the uterus. The age of a human ovum, 

 like that of the lower mammalian animals, whose early embry- 

 ology has been sufficiently studied, can probably be best estimated 

 from the stage of development of the embryo proper, but the data 

 in this respect as to very young human embryos are insufficient. 



