STUDIES IN MAMMALIAN EMBRYOLOGY. 349 
placentation of Cavia and other Rodents. Duval writes 
(Comptes Rendus de la Société de Biologie, 1887, p. 149) 
concerning Cavia: “Le tissu ectodermique du suspenseur 
(our trophodisc) se vascularise par des vaisseaux venus de la 
mére: au quatorziéme jour ce suspenseur forme un cone de 
trois millim. de diamétre & sa base, constitué par des cellules 
ectodermiques creusées de lacunes intercellulaires remplies de 
sang maternel. Ces cellules ectodermiques paraissent fusion- 
nées en un réseau de travées protoplasmatiques semées de 
noyaux, sans quw’il soit possible de distinguer les limites de 
chaque cellule correspondant & chaque noyau.”’ In the rabbit 
(where Selenka does not describe a trophodise, although in his 
diagrams he designates the outer Jayer of “ Deckzellen” by the 
same blue tint that distinguishes the “ Trager” of the other 
Rodents), Duval finds a similar arrangement, remarking 
(l. ¢., p. 427) of the two genera: “ Dans lun comme dans 
Yautre le fait essentiel est la présence de lacunes pleines de sang 
maternel dans une masseectodermique d’origine embryonnaire.” 
Half a year after this (February, 1888) my own observations 
on the hedgehog had so far advanced that I could publish the 
fact,! without any further comment, that maternal blood 
penetrates into the wall of the blastocyst of Erinaceus in very 
early developmental stages. This was somewhat more circum- 
stantially described at the Anatomical Congress in Wiirzburg, 
and subsequently in the ‘Anatomischer Anzeiger,’ of July, 
1888 (p. 510), where I wrote: “The outer wall of the blastocyst 
is thickened (three or four cell-layers) and characterised by 
spacious lacune. To this external epiblastic layer I wish to 
give the name of the Trophoblast? . . . . in the earliest 
1 ©Proc. Verb. Koninkl. Akad. van Wetenschappen,’ Amsterdam, 25 
Februari, 1888. 
2 «Tt appears to me to be practical to introduce this name into mammalian 
embryology, in order to indicate by it the epiblast that does not take part 
in the formation of the embryo. That what has hitherto been successively 
indicated as Reichert’s and Rauber’s cells, as ‘Trager’ (suspenseur), as 
Deckschicht, Ektodermawulst, horse-shoe-shaped proliferation, &c., would 
all, as belonging to the peripheral epiblast, fall under the designation of 
trophoblast. Even in the opassum Selenka described proliferations of the 
