Embryonic Development in Man. 365 



closed, and there is no amniotic duet. An allantoic duct is present. 

 The embryonic coelom is not yet indicated. 



Three embryos not considered in the "Normentafeln" are worthy 

 of note ; these have been described by Leopold, Teacher and Bryce, 

 and Jung, respectively. 



Leopold's small ovum, which forms the basis of a monograph 

 published in 190(5, was obtained from a young woman who com- 

 mitted suicide by taking phosphorus. After a prolonged search 

 of the interior of the uterus, Leopold found at the posterior wall 

 of the corpus a small point, somewhat lighter than the surrounding 

 tissue. A cubical piece of tissue containing this lighter point was 

 properly fixed and cut into serial sections, each five microns thick. 

 One hundred and sixty sections showed a very small cavity, which 

 presented the following measurements : Length, 1.4 mm. ; height, 0.9 

 mm. ; thickness, 0.8 mm. In no section could Leopold find any- 

 thing like an embryonic shield or an amnion, and hence he himself 

 raises the question whether this ovum may not be a pathologic 

 specimen. 



We most decidedly believe that Leopold's small ovum must be 

 looked upon as pathologic. The absence of the embryonic shield 

 must favor such a suspicion. We are either, it appears, dealing with 

 some profound changes in an ovum, due to phosphorus poisoning, 

 or possibly with the first stages of what would have been a hydatid 

 mole. 



Since Leopold published this monograph, it has generally been the 

 tendency of those writing on the first stages of human placentation 

 to discard his specimen from the list of young human ova. This 

 is done by Jung, and we have one year previous to this author 

 placed ourselves on record in the same sense. 



Bryce and Teacher^ have recently published an account of an 

 ovum which they believe to be between thirteen and fourteen days 

 old, and one day younger than Peters' specimen. They received 

 their specimen in "a mixture of urine and blood clot," in which 



°Bryce, Thomas H., and Teacher, John H. : Contributions to the Study of 

 the Early Development and Embedding of the Human Ovum. Glasgow, 

 1908. 



