202 
J. BEAliD. 
ganglionic Anlagen, I may refer to figs. 97, 98, 99 and others, 
more especially figs. 97 and 98, in which the “ Zwischenstraug ” 
and the ganglionic Anlagen can he seen in the same figure, and 
where they are entirely distinct and separate. 
When we turn to Professor His’s researches on the cranial 
ganglia of the Chick (Nos. 28 and 29), we find that he was a 
little more fortunate in seeing some of the true facts. But 
here again his theory influenced his interpretation of the facts. 
The foldings of an elastic plate by which, as is well known. 
Professor His explained all embryonic phenomena 1 (No. 31), 
must also find their application in the formation of the cranial 
ganglia. It is not merely in the assumption of such a folding 
in of the epiblast of the head to form the gangliouic Anlagen 
in his “ Zwischenrinne " that His is in the wrong; he has 
actually figured such a Zwischenrinne (No. 29, PI. XVII, figs. 
3, by Cy d, (?, /). 
I have made a very large number of sections through the head 
region of Chick embryos (well preserved) in this stage, and as 
the result I do not for a moment hesitate to say that the 
Zwischenrinne of His has no existence. On the contrary, in 
the head just as in the trunk, as the result of the separation 
of the ganglionic Anlagen from the epiblast, a “ Zwischen- 
straug ” may be formed (figs. 63, 97, 88); but this structure 
also plays no part in the formation of the ganglia. If Pro- 
fessor His had not assumed or believed in the existence of this 
“ Zwischenrinne,” and if he had left the “ elastic plate ” out 
of question and acknowledged the proliferation of a certain 
portion of the inner epiblastic layers to form the ganglia, he, 
who certainly was the first to see some of the true appearances 
on the Chick, would also have been the first to ascribe their 
true epiblastic origin to the cranial ganglia. But under the 
dominance of his theory he believed he saw structures 2 which 
1 This “ Mechanische Auffassung ” lias unfortunately more influence on 
Professor ilis’s results than his conception of the great value of comparative 
embryology, to which he lays claim in p. 405 of his recent critical study. 
2 One must bear in mind that the sections of those days were nothing like 
as good as those a fair worker can now make. 
