Literary Notices. xxvii 



first of considerable size and is hollow, as is the case thr oughout life in 

 Nedurus and Proteus. Soon a degeneration takes place which continues 

 until a mere thread remains and the lumen entirely disappears. From 

 the comparison Burckhardt infers that the accommodation tea dark habitat 

 is phylogenetically much earlier in Proteus than in Ichthyophis in which 

 the larva may have functional eyes. 



The meroblastic development of the Ichthyophis permits the develop- 

 ment of the head in a way more nearly like that of higher vertebrates than 

 is the case in other and especially holoblastic amphibians. . The cephalic 

 flextures are specially well developed although they afterwards become 

 obscured. 



Among the results of particular interest is the identification of J acob- 

 son's organ with a special branch of the olfactory as in reptiles. The 

 paper is accompanied by two plates. 



The Innervation of the Electric Organs of P^ishes. i 



In the Mormyridoe, which Prof. Fritsch has specially studied in Egypt, 

 the innervation of the caudal electric organ is not via the lateral line 

 nerve but by means of special electric nerves which emerge as spinal 

 roots from- the spinal cord and form a dorsal and ventral axial trunk. 

 After seeking in vain for the origin of these fibres for some time it was 

 discovered that the electrical nerve-fibres arise as broad undivided axis- 

 cylinder processes of gigantic ganglion cells which in spinal regions com- 

 pletely fill up the gray substance of the spinal cord and emerge through 

 the anterior roots. What is of particular interest just now is the fact that 

 the protoplasmic processes of these large cells anastamose with each other 

 forming an "eng geschlossenes, wahres Geriist, und erscheinen zu 

 gemeinsamer Arbeit verbunden." This affords a new evidence that the 

 separation of protoplasmic and nervous processes is artificial as claimed by 

 more recent followers of Golgi. The electrical nerves form a remarkable 

 chiasm outside the vertebral column so that the left electric organ is partly 

 innervated from the right side and vice versa. 



1. Feitsch, (t. Weitere Beitrage zur Kenntniss der Scliwach Electrischen Fische. 

 Mat. 11. naturw. Mittli, Berlin Akad, Nov., 1891, p. 439. Figures in text. 



