No. I.] THE CRANIAL NERVES OF AMPHIBIA. 137 



contrast to the second root where these fibres passed through 

 the upper part of the ascending Trigeminus. In the Golgi 

 preparation, from which the figure is taken, a considerable 

 number of the fibres from the fasciculus communis are impreg- 

 nated and appear as straight, delicate fibres proceeding parallel 

 with each other and forming a compact bundle. Carmine 

 preparations show the same characteristic appearances for the 

 fibres from this source, and Weigert preparations of the frog's 

 brain show that here these fibres, proceeding in a similar 

 manner, are fine and delicately sheathed. In the Golgi prepara- 

 tion only a small proportion of the fibres composing the bundle 

 from the ascending Trigeminus is impregnated, and these 

 exhibit a marked contrast to those from the fasciculus com- 

 munis. They are coarser, more varicose, and have a more 

 irregular, sinuous course. The bulk of this latter bundle issues 

 slightly cephalad of the bundle from the fasciculus communis. 

 In addition to these two components there is a more ventral 

 motor rootlet, similar to that emerging with the second root. 

 It is a possibility that some ascending Trigeminus fibres also 

 pass out with the second root, but this is not certain. 



ThQ fourth root is indicated in Fig. 35. It is separated by a 

 well-marked interval from the third root. Here, also, the fibres 

 from the fasciculus communis curve down, around, and below 

 the ascending Trigeminus in several compact bundles. No 

 fibres emerge from the ascending Trigeminus, and there is 

 present here, also, a ventral rootlet. As can be seen in the 

 figures, the bundles from the fasciculus communis entering 

 these roots diminish in bulk as we proceed caudad, i.e., those 

 entering the caudal roots are smaller. Emerging with the 

 ventral rootlet of the fourth root, and further caudad than the 

 other bundles, is sometimes to be seen still another very 

 minute bundle from the fasciculus communis. 



The fifth root, emerging some distance caudad of the fourth 

 root, seems to derive its fibres from one source only. Its 

 fibres can be traced caudad in the medulla some distance 

 until lost among the longitudinal fibres of the lateral region of 

 the medulla. This is the bundle which Osborn has identified, 

 though erroneously as we shall see, with the fasciculus solitarius, 



