107 



den primären Epiblast, von dem sich durch Abspaltung der Epiblast 

 des Fruchthofes nach innen abhebt, zu benennen vorschlug)". 



Again in the article on the placentation of Erinaceus in Vol. 30, 

 Pt. 3 (1889) of the Quarterly Journal of Microscopical Science where 

 the definition was reproduced, it is insisted upon (p. 298) that "the use 

 of the name trophoblast will render unnecessary circumlocutory ex- 

 pressions as: outer epiblastic layer of the blastocyst, primitive exo- 

 chorion, &c." Further argumentations on p. 299, in which the allanto- 

 idean and the omphaloidean trophoblast is defined, leaves not the faint- 

 est doubt as to what the name trophoblast has originally stood for. 



Five years later (1894) in an article Spolia nemoris which 

 appeared in Vol. 36 of the Quart. Journ. of Microsc. Science, I again 

 insisted (p. Ill) that "new and valid reasons are thus accumulated for 

 designating the outer layer of precociously segregated epiblast cells 

 that form the wall of this vesicle [the early mammalian blastocyst] by 

 a separate name , [for which] I have proposed the name of tropho- 

 blast". Somewhat further is added (p. 112): "In Tupaja and Tarsius 

 portions of the trophoblast undergo very active proliferating processes 

 preparatory to the placentary fixation of the blastocyst , whereas in 

 my former papers I have described the same activity for Erinaceus and 

 Sorex". 



Finally in 1895 (Verhandel. Kon. Akad. v. Wetenschappen, Amster- 

 dam, Vol. 4, No. 5, p. 18) I reaffirm that: "Die von mir Trophoblast 

 genannte Keimschicht ist ... . die äußere Schicht der Säugetierkeim- 

 blase, welche vor der definitiven Ausbildung des formativen Epiblastes 

 diesen sowie die Hj^poblastanlage umhüllt und an der Bildung des 

 Embryos überhaupt keinen Anteil nimmt". 



In this latter paper I have for the first time asserted that in my 

 opinion the Sauropsidan arrangement as well as that of the Ornitho- 

 delphia cannot possibly be looked upon as ancestral to what we find 

 in the monodelphic (and didelphic) Mammalia and that on the contrary 

 the trophoblast (1. c. p. 57, No. 7) is a precociously segregated larval 

 envelope which encloses an inner cell-mass out of which the embryo is 

 going to be built up. I have at the same time drawn a comparison 

 between the mammalian trophoblast and the "Deckschicht" in Amphibian 

 development and have also drawn attention to those cases, where rem- 

 nants of a trophoblastic layer could be detected in the Sauropsida. 



Only in 1902 however have I gone yet further back and leaving 

 the recent amphibia out of the ancestral line I have attempted to draw 

 a comparison between the trophoblast (and the other fetal membranes 

 coexistent with it) of the Amniota and larval envelopes of invertebrate 

 predecessors (Verhandel. Koninkl. Akad. van Wetensch. to Amsterdam, 

 Vol. 8, 1902, No. 6, p. 53). 



It has now been shown that since the first introduction of the 

 name trophoblast, sixteen years ago, my own definition and interpre- 

 tation of it has not undergone any alteration, although advances have 

 been made in the appreciation of its theoretical significance. 



And it is for this reason difficult for me to understand that the 

 name has been misunderstood both by embryologists and by gynae- 



