874 



Nachdruck verboten. 



A contril)ution to the morphology and derelopment of the 

 nerTous system of Vertehrates. 



By J. Beaed. 

 Aus dem Anatomischen Institut zu Freiburg i. Br. 



I. The peripheral nervous system. 



In spite of the numerous investigations which have already been 

 made on the development of the peripheral nervous system of Verte- 

 brates — investigations some of which bear the names of distinguished 

 morphologists — no really satisfactory account has yet been given. 

 To convince oneself of the truth of this one need only turn to the 

 latest embryological textbook, that of Prof. 0. Hertwig. 



Speaking as one who has paid some little attention to the peri- 

 pheral nervous system and its sense organs I confess to finding the 

 chapter on the peripheral nervous system in Hertwig's book among 

 the most unsatisfactory in the whole work. Indeed, the author him- 

 self seems to have found considerable difficulty in stringing together 

 a consistent narrative from the chaotic literature of the subject. 



Some time ago I set to work on a long meditated plan of inves- 

 tigating the very first beginnings of the peripheral nervous system, 

 more especially for the of purpose unravelling some of the complex pro- 

 blems presented by the cranial ganglia. In ray former work I had 

 paid very little attention to the spinal ganglia except, to note the 

 points in which their development differed from that of the cranial 

 ganglia, and the time seemed fitted for a thorough investigation of them 

 as well as of the cranial ganglia. 



Kleinenberg's magnificent embryological work on the nervous 

 system of Annelids also acted as an incentive to renewed work; for 

 at once the idea arose that the peripheral nervous system of Verte- 

 brates might turn out to be for more complex than hitherto supposed, 

 and points of resemblance between it and that ofjAnnelids might be dis- 

 covered. Then there was the Zwischenstrang of His to be thoroughly 

 examined; for, beyond baptising it and sending it into the scientific 



