THE EMBEDDING OF THE OVUM. 49 



the arch, where the ovum has entered, a blood coagulum is found 

 serving as a protective covering, which in Peters' specimen re- 

 sembles a mushroom, in mine a caterpillar with a large head. 



This variation in shape so well pronounced in all my sections, 

 calls for a more appropriate name. Peters' term "Gewebspilz" 

 certainly cannot be applied to my specimen. With the idea that 

 such an expression should be applicable to all later cases it 

 seemed most natural to select the term "fibrinous cover" (Fibrin 

 decke). Whatever its name may be, however, the fact remains 

 that in these two youngest human ova it was present, large and 

 well developed. This explains the peculiar rests of fibrin found 

 on the top of the ovum in older specimens, as, e. g., described in 

 my atlas (Uterus und Kind, Plate I). 



As first shown by Peters, our specimen also proves that the 

 old circumvallation theory of the formation of the reflexa is in- 

 correct, but still a reflexa is present. If one drops a stone into 

 the water the latter closes over it and if an earth worm bur- 

 rows itself into the ground, the hole made by it will again grad- 

 ually be filled with the loosened soil. 'The rapidity with which 

 it becomes closed will depend upon the character and structure 

 of the soil. 



It seems permissible to call rcflc.va in Peters' and my speci- 

 men, those decidual arches which approach each other approxi- 

 mately over the center of the ovum. One must, however, keep 

 in mind that these arches have not newly formed and closed over 

 the ovum, but that as a matter of fact, they have existed from 

 the first beginning and that through them the minute ovule has 

 burrowed its way. The arches become higher the more the 

 ovum grows. It is obvious that the opening between the arches, 

 i. e., the passageway of the ovum, finally again becomes closed 

 by either a fibrinous plug or a fibrinous band. 



In the following it will be shown that the great similarity ex- 

 isting between the microscopic pictures of Peters' and my speci- 

 men, leads to a like interpretation of the findings. 



Peters (pg. 28) emphasizes that his ovum has become im- 

 planted in the swollen mucosa near a furrow, the same has oc- 

 curred in my case. Since the uterine mucosa prepared to receive 

 the ovum is traversed by numerous deep furrows, he thinks it 

 might possibly happen "that the minute human ovule could be 

 caught in such a groove and then actually could become em- 

 bedded (exactly like the ovum of the erinaceus) if the edges 

 of the furrow coalesced and finally closed." "In such an in- 

 stance, however, the ovum would be completely encircled by a 



