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Annelids and Vertebrates, came to an opposite opinion, 
after it had been demonstrated that in Vertebrates several 
of the cranial ganglia originate parnly from the neural ridge 
and partly from the ectoderm, viz: from ganglionic prolifer- 
ations of either transient or permanent lateral organs. He 
now assumed that originally the lateral organs kad some 
physiological connection with tbe gills, over which they are 
situated in the craníal region and which are innervated from. 
their ganglia. He therefore changes their name into branchiíal 
sense-organs. Ontogenetically we first see the lateral organs 
appear on the head and then, together with the outgrowing 
ramus lateralis vagi, extend backwards over the trunk. From 
this mode of development BEARD deems it probable, that they 
were originally restricted to the gill-bearing region and from 
here have only secondartily spread over the trunk. “Damit 
wird aber”, EISIG infers. “eine ontogenetische Thatsache 
willkürlich, das heisst ohne Berücksichtigung aller im Wege 
stehenden Schwierigkeiten, ins Phylogenetische übersetzt. 
Und die Haup:schwierigkeit besteht darin, plausibel machen 
zu können, wie denn eigentlich dieses ursprünglich allein 
am Kopfe entwickelte Seitenorgansystem dazu kommen 
sollte, sich secundär in segmentaler Anordnung auf den 
umpf auszudehnen, auf denjenigen Körpertheil der doch 
notorisch als der phylogenetisch ältere und einfachere zu 
betrachten ist”. This latter opinion we cannot share from 
the point of view of our theory, the soma of Annelids and 
Vertebrates is no doubt phylogenetically younger than 
the pros‘omium and not older than the segmented, part of 
the head which, as we shall see, in several respects has 
even retained a more primitive character than the rest of 
the trunk. Yet in the spreading of organs, originally 
restricted to the foremost part of the body, over the trunk 
and in their assuming a metameric arrangement BEARD also 
acknowledges a curious fact. The ontogenetic development 
of the lateral organs from the head backwards over the 
trunk is accounted for by EISIG in this way, tnat the former 
condition, in which they originated independently in all 
segments, is no longer recapitulated in the trunk in conse- 
quence of the reduction of their segmental innervation, and 
that they now arise in connection with the collector-nerve 
from front to back. 
In any case, the homology of the lateral organs in Verte- 
brates and Annelids remains somewhat questionable, and it 
