434 
stances have combined to flatten out the diverticula and that the 
“Zwischenplatte” appears in sections like fig. B or figs. 11 and 12 of 
my paper only slightly arched will seem to a morphologist no diffi- 
culty in the way of regarding the latter as representing the wall of 
the diverticula. It is simply a question of greater or less curvature. 
The proliferation of mesoblast cells from the wall of the diverticula 
which seems to take place in Amphioxus only after they have been 
cut off from the archenteron is begun in Reptilia long before that 
event and this part (mgr) standing out prominently in fig. B is taken 
by Wırr for the oldest part of the gastral mesoblast. This, how- 
ever, is a misconception, I think. When the nature of the “Zwischen- 
platte” as representing the wall of the diverticula is remembered, 
not only the part marked mgr but the whole “Zwischenplatte” together 
with mgr to the point where the gut-hypoblast (e’) begins ought to 
be regarded as belonging to the mesoblast in fig. B just as much as 
in fig. E. The part mgr has proliferated from the outer wall of the 
diverticulum towards the periphery, and can not be the ol- 
dest part of the gastral mesoblast as it must be more recent 
than the wall of the diverticulum. This course of reasoning obliges 
one to come to the conclusion that the Hrerrwia’s theory of the 
mesoblast formation is strictly applicable to Gecko and Clemmys. 
When the nature of the intermediate plate (Zwischenplatte) is 
remembered, there is practically no difference between “Divertikel- 
bildung” and “Septenbildung” A fold is needed to snack 
the outer limit of the diverticulum, and whether the presence of the 
fold is emphasized or the diverticulum is pointed out as the essential 
feature does not alter the facts of the case much. Wırn’s objection 
to the Hertwic’s theory may therefore be only an apparent one. 
I have unfortunately not seen GÖTTE’s paper on Petromyzon to which 
Wit refers, but I am acquainted with the process of the mesoblast 
formation in that animal, as a former pupil of mine, Mr. S. Harra *) 
investigated just this point in our lamprey. There were not only 
nothing in it that could interfere with the acceptance of the views 
which I advocated in my paper”), but many things which confirmed 
them strongly. 
March 7, 1893. 
1) S. Harra, On the Formation of the Germinal Layers in Petro- 
myzon. Jour. Sc. Coll., Imp. Univ., Japan, Vol. V, Pt. 1. 
2) K. Mrrsuxugi1, On the Paired Origin of the Mesoblast in Verte- 
brata. Anat. Anz., Jahrg. VI, Nr. 7. 
