V. KuPFFEK, Cranial Nerves of Vertebrates. 251 



into the connections under discussion and accordingly origi- 

 nate through a union of central with epidermoid elements, 

 Froriep indicates the gang, geniculi, gang, petrosum and 

 gang, nodosum; they exhibit the phylogenetic remnants of 

 former sense organs; they cannot consequently be considered 

 homologous with the spinal ganglia, and thereby fails a chief 

 support of the spinal hypothesis. The nerves of the visceral 

 arches as segmental nerves can no longer be identified with 

 spinal nerves. 



In a long series of works J. Beard(') has handled the 

 problem of the cranial nerves and their sensory end organs. 

 Torpedo ocellata furnished the principal object of Beard's 

 investigations, although sharks, teleosts. Amphibia and Am- 

 niota (Lacerta, chick) came under consideration. In the 

 main. Beard follows, in facts as well as in the interpretation 

 of the conditions, the observations and conceptions of the 

 previously mentioned investigators, but also contributes the 

 fact that the participation of the epidermis in the formation 

 of ganglia and nerves occurs also in the region of the 

 trigeminus. 



The complete representation of the development of a 

 dorsal cranial nerve would, according to him, be as follows: 

 The rudiments of the ganglia in the head, agreeing through- 

 out with those of the spinal nerves, arise as differentiations 

 of the inner layer of the ectoderm, just outside the limits of 

 the neural plate. They separate from the ectoderm, become 

 displaced upwards in the closing of the neural tube, and 

 come to lie between its lips, but are always distinguishable 

 from it. After the closure of the neural tube, the portion of 



I ''On the Segmental Sense Organs of the Lateral Line and on the Morphology of 

 the \ertebrate Auditory Organ," Zool. Anz., 1884, p. 123; "The System of Branchial 

 Sense Organs and their Associated Ganglia in Ichthyopsida," Quart. Jour. Mic:osc Sc, 

 1886. Vol. XXVI, new series, p. 95 ; '• The Ciliary or Motor-Oculi Gangl. and the Gangl. 

 of the Ophthal. Profund. in Sharks," Anat. Anz., 1887, p. 585; " The Old Mouth and the 

 New," Anat, Anz., 1888, p. 15 ; "A Contribution to the Morphology and Development of 

 the Nervous Syst. of Verteb.," Anat. Anz., 1888, pp. 874, 899; "The Development of the 

 Peripheral Nerv. Syst. of Vertebr ," Quart. Jour. Micros. Sc, Vol. XXIX, new series, 

 1889, p' 153; "Prof. Rabl on the Mode of Development of the \'ertebrale Peripheral 

 Nervous System," Anat. Anz., 1890, p. 125. 



