184 STRONG. [Vol. X. 



fibres to any cells. Koppen (35) seems to refer to this tract 

 when he says : " Schon kurz vor der Eroffnung des Central- 

 canals, bald nachdem die letzte dorsale Wurzel das Riicken- 

 mark verlassen hat, tritt dorsal in der grauen Substanz ein 

 Langsbiindel feiner Fasern zu Tage, eingelagert in einer 

 dichten grauen Masse, die sich kreisformig von der iibrigen 

 abgrenzt (Substantia gelatinosa Rolando), s. Taf. I, Fig. 3 S. 

 g. R. Diese Substanz ist nur die Fortsetzung der gelatinosen 

 Masse, welche wir im Riickenmark, innen vor den dorsalen 

 Wurzeln, fanden. In ihr zeigen sich nun einige Langsfasern, 

 ein attfsteigendes Wurzelbundel des Vagus tmd des Trigeminus. 

 Es riickt allmalig aus der grauen Substanz immer mehr dem 

 Rande zu und liegt schliesslich median von dem Seitenstrang 

 und den Dorsalstrangen." Koppen seems to have recognized 

 the fact that this tract is continued cephalad of the IX + X but 

 refers it to the Trigeminus instead of the Facialis. As he 

 seems to have overlooked also the motor bundle of the VII 

 which makes its exit with the VIII or, rather, refers it to 

 the VIII, he is compelled to seek for the VII in the V and 

 derives both the VII and the motor portion of the V from the 

 motor nucleus of the V. Osborn remarks : ** At this point he 

 (Koppen) fails to distinguish between the Facial and Auditory 

 elements, for his dorsal Auditory root, p. 9, is probably the 

 main portion of the Facial. This error, if error it be, arises 

 from the fact that he expects to find the facial a purely motor 

 nerve, p. 10." Koppen must be acquitted on this point, 

 however, for the **main portion of the Facial" referred to 

 (Osborn's '' J u and /" = '' dorsal VII" to lateral sense organs) 

 has disappeared in the frog. Koppen's real error is in not 

 distinguishing between the V and VII and into this error he 

 may have been led as Osborn suggests. 



Osborn gives a correct account of the exit of this bundle, 

 but was unable to determine whether it ultimately went to 

 the VIII or the VII. As shown above, the latter is the case. 

 There exists a remarkable difference, however, between the 

 exit of the fasciculus communis in Urodela, on the one hand, 

 and in Anura and tadpoles on the other. In the former the 

 exit of this fasciculus to the VII takes place just dorsal to the 



