No. I.] THE CRANIAL NERVES OF AMPHIBIA. 1 31 



connection an observation of Volkmann (64) may be cited. 

 Volkmann found, by stimulation, that the communicating 

 branch from the IX + X did not contain motor fibres. 



These observations are partially checked in another way by 

 a most beautiful extirpation experiment performed by nature. 

 In the frog the lateral line system of sense organs disappears 

 and, as I have verified myself in the common frog, in the toad, 

 and in one of the Hylidae, the dorsal VII (VII b) disappears 

 also. Consequently the various rami (see table below) derived 

 from this root are wanting in these forms, but on the other 

 hand, such cutaneous branches as do not belong to this system 

 persist. Accordingly we find in the frog, for example, a 

 cutaneous branch from the R, hyoideus. Furthermore, this 

 affords a firm basis in determining the R. auricularis VII (17) 

 and in excluding, as possible homologues, those cutaneous 

 branches derived from the dorsal VII. 



The question of certain homologies is discussed in another 

 portion of this paper. Some, however, are assumed in the 

 table given here, which presents in a convenient form an 

 analytical summary of the N. facialis. 



I may add that an examination of serial sections through the 

 brain and proximal portions of the nerves of the frog, stained 

 by Weigert's method, show very clearly the two components 

 of the VII, before joining the V, namely, on the outer side 

 the coarse-fibred motor part and mesad the fine-fibred fasciculus 

 communis component. Although somewhat out of place here, 

 it may be remarked that a bundle of fibres can be traced in 

 the V which preserve their integrity through the Gasserian 

 ganglion entering the R. mandibularis, and which, tracing them 

 proximad, appear to be derived from the motor root of the V. 



In Amblystoma larvae the relations of these roots are some- 

 what different. They are shown in the figure occupying the 

 corner of the chart (PI. XII, C). Here the principal differ- 

 ence lies in the fact that the VII is not pushed forward into 

 the V. There are also other differences : in the Amblystoma 

 larva the dorsal VII is considerably larger than in the tadpole, 

 while the Auditory is smaller relatively, not only to the dorsal 

 VII but to the medulla. Furthermore, it is separated from 



