e” sp So mp e” co INIT. 
closely with those given by WıLL that we may safely take it for 
granted that they are essentially correct. My interpretation of these 
facts differed, however, from Wırr’s: I saw in them a renewed and 
emphatic confirmation of the view that the gastral mesoblast arises 
as the wall of diverticula of the archenteron. It seemed to me 
that Clemmys showed in this respect very primitive state of things 
which preserved beyond expectation the condition in Amphioxus as 
given by HatscueK. Now, after reading Wırr’s paper, I am still of 
the same mind; I may therefore be permitted to point out what, I 
venture to think, are misconceptious on the part of Wırr. I think, 
the essential point of difference between WıLL and myself is in the 
way in ‚which we regard that stretch of epithelium that lies between 
the Chorda-Anlage and the point of the origin of the lateral 
folds — Wırr’s “Zwischenplatte”. In the paper of mine above re- 
ferred to, I went over this point very carefully and I think, I proved 
that this stretch of epithelium ought to be regarded as equivalent to 
the mesoblast diverticula of the archenteric wall in Amphioxus (the 
darkly shaded parts in figs. 69 and 70, Herrwie’s Lehrbuch). For 
the arguments I advanced, I must refer the reader to the original 
paper. I shall only remark here that there are actually sections of 
Clemmys embryos in which this stretch arches upwards and forms a. _ 
deep diverticulum of the archenteron, directly on each side of the 
Chorda-Anlage. See for instance fig. 23 of my paper copied also 
in a short notice which I published in this journal!). That circum- 
opens below. I am, however, persuaded that Wut is correct in his 
statements in regard to this. 
1) K. Mirsvxvrr, On the Paired Origin of the Mesoblast in Verte- 
brata. Anat. Anz., Jahrg. VI, Nr. 7. 
28 
