188 



acusticum in other bony fishes. The relations of the visceral and so- 

 matic sensory columns in the myelencephalon of Lampetra are illust- 

 rated in a diagram in Fig. 8. In this figure the hindbrain is outlined 

 as seen from above and the extent of the visceral sensory column is 

 indicated by shading with oblique lines, the somatic sensory column by 

 horizontal lines. The visceral sensory fibers are drawn as very fine 

 lines, the somatic sensory fibers as coarse lines. The cranial nerves 

 are numbered V, VIl, VII 1.1, VIII, IX, X. I find nothing in Tret- 

 jakoff's description to show that he has seen any part of this visceral 

 sensory system. 



Fig. 5. A part of the left side of the section from which Fig. 4 was taken. 

 Four fibers of the N. glossopharyngeus are giving off end branches in the region cor- 

 responding to that drawn in Fig. 4. This is the visceral sensory column and these 

 are visceral sensory fibers. The irregular shaded area in the course of the fibers is a 

 mass of precipitate. Magn. about 400 diam. 



Schilling recognized the visceral sensory component of the Nn. 

 facialis, glossopharyngeus and vagus and his description, although 

 brief, agrees with that given by me. That Tretjakoff should have 

 overlooked these components is readily explained on the supposition 

 that the very fine fibers were not stained in his preparations. That 

 the author should not have had a sufficiently critical attitude toward 

 his own work to recognize that something was lacking in his de- 

 scription of these nerve roots was perhaps due to two things. First, 

 the presence of a cutaneous component in each cranial nerve (V, VII, 



