ANATOMY AND CLASSIFICATION OP THE ARENICOLID^. 495 



Thus in the earthworm Apathy states (1897, p. 624), "Die 

 Neurochorde enthalten nJimlich ausser sehr dunnen Prirnitiv- 

 fibrillen sine Anzahl starker, meist trotz ziemlicher Streckung 

 des Thieres, sehr kleinwellig, aber im ganzen in gerader 

 Richtung verlaufender Primitivfibrillen in axialer Lage, 

 und diese starker Primitivfibrillen sieht man in frontalen 

 Schnitten besonders deutlich (also auch in transversalen 

 oft sehr schon) an verschiedenen Punkten aus dem Neuro- 

 chord durch diesen dicke Gliascheide heraustreten, und in 

 der Fasermasse in transversalen Richtung eine Strecke weiter 

 gehen.'^ But no reference is made to the fact ascertained by 

 Friedlander and Cerfontaine that these giant-fibres, neuro- 

 chords, or " sensorische Schlauche," by whatever names they 

 are called, have been traced to what the two latter authors 

 believe to represent ganglion-cells, and with which these 

 fibres ai'e certainly connected. 



Lastly, in Lophius, in which, as is well known, giant 

 cells and fibres have been discovered by Fritsch (1886), 

 Apathy describes giant-fibres in the dorsal spinal nerve- 

 roots, and states that he traced them from the large pyriform 

 ganglion-cells discovered by Fritsch, and out of the dorsal 

 furrow of the cord into the dorsal root (which contains 

 sensory and motor fibres). He adds, however, that he is 

 about to re-examine this result. Though their origin may 

 be doubtful. Apathy states on the ground of their structure, 

 that the giant-fibres of Lophius are also "sensorische 

 Schlauche,'' and equivalent to the structures so named in the 

 nerves of Hirudo. A noteworthy distinction to which he 

 does not draw attention, is the central course of these fibres 

 in Lophius. For no one has, as yet at least, described a 

 T-shaped bifurcation followed by subsequently branching, 

 and termination by minute fibrils in the neuropile of the cord. 



Apathy's conclusions, in fact, may be summarised thus. 

 Giant-fibres are a normal constituent of the ordinary mixed 

 nerves of leeches, Oligochagtes, of the dorsal (also mixed) 

 nerves of Lophius, and of the nerves of Astacus and 

 Palesmon. These giant-fibres are better called sensory 



