MORPHOLOGICAL STUDIES. 
157 
never entertained the question of the epiblastic origin, apart 
from the central nervous system, of the neural ridge, the 
accusation is unjust; for I can assure Professor Gegenbaur that 
such was far from being the case. 
And, as it now turns out, van Wijhe’s objection that 
the main root of the nerve arises as an outgrowth of 
the central nervous system will not hold, for the origin of 
what he calls the main root, in the case of the cranial and 
spinal ganglia, is demonstrably in principle in accordance with 
the account of the development of the olfactory nerve and 
ganglion, as given by van Wijhe himself. In fact, in the 
main, I accept gladly and gratefully van Wijhe’s 
researches on the olfactory organ as supporting and 
confirming my view of its homology. But for a fuller 
discussion of this matter, I must ask the reader to wait till 
the ground has been cleared by the detailed account of the 
researches on the very first origin of the cranial ganglia in 
nearly all classes of Vertebrates. 
And now a few words on the second work, which was the 
great stimulating agent in impelling the researches about to 
be recorded. If the reader w'ill refer to the introduction of 
my work on the branchial sense organs (No. 6) he may read that 
“ at present w r e are acquainted with no Invertebrate nervous 
system which is built on the same plan as that of Vertebrates.” 
This conclusion led me to take up an attitude of expectancy 
rather than of negation towards the Annelidan theory of the 
origin of Vertebrates. And while I felt compelled to doubt the 
homology between the “ Seitenorgane ” of the Capitellidse 
and the “ Seitenorgane ” of Vertebrates, so ably maintained 
by Eisig, I was not quite without hopes that further researches 
on Invertebrates might reveal facts on which a comparison of 
the peripheral nervous system of Vertebrates, with some allied 
stock of Invertebrates, probably Annelids, might be main- 
tained. 
In October, 1886, appeared Kleinenberg’s epoch-making 
researches on the development of Lopadorhynchus (No. 41). 
I shall find plenty of opportunity in this and some of the fol- 
