( 1079 ) 
In Dasyurus, as Hint repeatedly says, what is by him called the 
formative hemisphere (itself a derivative of the belt of 8 smaller 
cells) of the hollow. blastocyst, fulfils the part that was just indicated 
for the Kutheria by italics, whereas the lower or non formative 
hemisphere of the _blastoeyst constitutes the trophoblast of the 
Metatheria, comparable to that of the Sauropsida and Prototheria 
and a fortiori also of the Eutheria *). 
Oo Ta 7 
given on p. ¢ 
My own interpretation of the Metatherian morula, 
of my article in vol. 53 of. the Q. Journ. and not based on any 
personal observations, has taken its starting-point from SELENKA’s 
figures of early Opossum blastocysts, about which Hir, expresses 
grave doubts and which he refuses to look upon as normal. So 
here the two specialists who have explained to us the early develop- 
mental phases of Marsupials are diametrically opposed, one (SELENKA) 
describing and figurine the presence — inside of the unilaminar 
blastocyst —- of a mothercell (Urentodermzelle) of the entoderm, 
whereas the other (Hur) is convinced that normally there is no 
cellular enclosure inside this unilaminar blastocyst wall of Dasyurus 
and thus no mothercell of any embryonic knob comparable to the 
“inner cell mass” of Eutheria in the Marsupials. 
For myself [have based my comparative considerations on SELENKA’S 
data, but have interpreted them differently, looking upon SELENKA’s 
“Urentodermzelle’ as the mothercell not of the entoderm only, but 
of the whole inner cell mass (embryonic knob). 
The fact that Prof. Hur does figure one case (I. ce. Pl. 3 Fig. 37) 
in which a Dasyurus blastoeyvst contained one big cell in its cavity 
and that therefore this case — emphatically stated to be abnormal 
by Hir — does present a certain amount of comparability with 
SELENKA’s figures above alluded to, made me all the more anxious 
!) There is a misunderstanding on p. 107 of Hitu’s latest paper as to my nol 
considering the extra-embryonal ectoderm of Sauropsida as trophoblast. This 
misunderstanding may have arisen in consequence of Hitt having cited the 
condensed text of my Boston address, while my original paper (Q. J. vol. 53 
p. 20, 24, 25) would have left no doubts in his mind and would at the same time 
have convinced him that the wonderful phenomenon in Dasyurus so excellently 
figured in his fig. 42—46, 48—50, has been welcomed by me as a beautiful 
confirmation of my contention that in Sauropsida and Ornithodelphia we ought to 
identify the so-called extra-embryonal ectoderm with the entire trophoblast of 
Eutheria. Here again the Rauber-cells of the rabbit, of Sorex among others have led 
Hint astray, as they have formerly done Bonner, and the intercalation of embryonal 
ectoderm into the trophoblastic outer layer has not been sufficiently kept in view, 
although L have particularly called attention to its details in Tupaja, Tarsius, Sus, 
Cervus and so many others. 
