451 
the invagination of the archenteron with the consequent establishment 
of the chorda-hypoblast, of the peristomal and gastral mesoblast, of 
the yolk- plug, and of the definitive or palingenetic hypoblast. The 
embryonic shield and the primitive knob form together a patch 
capped on the upper pole of the egg where nearly all the changes 
that are gone through by the whole egg of the Amphibia are per- 
formed. According to this view, the enclosure of the yolk in the 
Cheivnian egg is of a very different nature from the enclosure of the 
yolk in the Elasmobranchs. The former is a simple growth of the 
edge of the blastoderm and is of the caenogenetic character, while 
the latter is a part of the process of invagination and is of the 
palingenetic character. I find myself thus obliged to put aside the 
yolk-blastopore of BALFOUR in Sauropsida. 
Jan. 4, 1893. 
Nachdruck verboten. 
On Mesoblast Formation in Gecko. 
By K. MırsuguRı, Pu. D., Imperial University Tokyo, Japan. — 
With 2 Figures, 
Dr. Lupwic Wırr has recently published an important paper ') 
on the formation of the germinal layers in Gecko, and I was favored 
with a copy of it by the kindness of the author. In it, he sets forth, 
among other things, a somewhat novel view on the formation of the 
gastral mesoblast. According to him, a fold arises on each side in 
the wall of the archenteron at some distance from the median “Chorda- 
Anlage” (fig. B). The point where the fold arises corresponds to 
the place that formed the extreme lateral edge of the archenteric 
cavity, before the latter opened below into the subgerminal cavity. 
Before that event takes place, cells are already proliferated outwards 
from the laterale edge of the archenteron and when the latter breaks 
open below and the above-mentioned fold is formed, the proliferated 
cell-string (mgr) remains as the mesoblast. Wirt therefore considers 
this string (mgr) as the oldest part of the mesoblast (p. 101). 
The lateral folds now approach gradually the median “Chorda-Anlage”, 
1) Lupwic Witt, Die Anlage der Keimblätter beim Gecko (Platy- 
dactylus facetanus Scurers.). Zool. Jahrbücher, Abt. f. Anat. u. Ont, 
Bd. VI. 
