150 IRRITABILITY 



ered as completely dispensable and may, therefore, be omitted; 

 thus nothing remains of the "core model explanation" of the 

 conduction of excitation in the nerve. 



The results of continually increasing numbers of investigation 

 in recent times make it appear almost as a certainty that the ele- 

 mentary fibrillae in the axis cylinder are nothing else but skeletal 

 substances. IVolff,^ Verworn^ and others have first expressed 

 the view that the neurofibrillse must be looked upon as skeletal 

 fibers for the soft neuroplasm, and more recently Lenhossek^ and 

 especially Goldschmidt* have confirmed this assumption in detail. 

 Goldschmidt has shown by extensive comparative studies of cell 

 mechanism the role played by the neurofibrillffi in a physical con- 

 nection as internal skeletal formations, and has proved at the 

 same time, in complete unanimity with other investigators, their 

 continuity with other undoubted skeletal fibrillse. By this the 

 numerous combinations and speculations of Apathy and Bethe 

 concerning the part taken by the neurofibrillae have been rendered 

 untenable. In no case is there the slightest justification to regard 

 the apparent "Kernleiterstructur" of the nerve as the principal 

 condition for the process of conductivity, for should we dispense 

 completely with this point for the theory of the conduction of 

 the nerve, we can obtain, solely by the aid of the facts known 

 today in physical chemistry, the foundations for a theory of the 

 conductions of excitation which not merely renders the specific 

 case of the conduction of the nerve intelligible, but contains at the 

 same time the principles of the process of the conduction of exci- 

 tation for all living substance. 



On the basis of investigation in the physical chemistry on the 

 properties of semi-permeable membranes, we know that such 

 membranes produce an elective effect on the diffusion of dissolved 



1 M. Wolff : "Ueber die fibrillaren Structuren in der Leber des Frosches." Anatom. 

 Anzeiger Bd. 26, 1905. 



2 Max Verworn : "Bemerkungen zum heutigen Stand der Neuronlehre." Medicin. 

 Klinik, Jahrg. IV, 1908. 



3 M. V. Lenhossek : "Ueber die physiologische Bedeutung der Neurofibrillen." 

 Anatom. Anzeiger Bd. 36, 1910. 



4 Richard Goldschmidt: "Das Nervensystem von Ascaris lumbricoides und megalo- 

 cephala. Ein Versuch in den Aufbau eines einfachen Nervensystems einzudringen." 

 Ill Teil. Festschrift zum 60 Geburtstage Richard Hertwigs Bd. II, 1910, Jena. 



