NERVUS TERMINALIS IN AMIA 79 



laterally down between the secondary folds, as indicated by the 

 arrows in the figure, to emerge at the sides of the capsules into a 

 sort of drainage trough. From this trough the water can reach 

 the posterior opening and pass to the outside. The mid-rib is at a 

 lower level than the lateral ends of the secondary folds and some 

 of the water passes posteriorly along the mid-rib and directly 

 out between some larger folds there, or over them. A mucous 

 substance is continually thrown out from the nasal epithelium 

 and soon entangles the powdered carmine in ropy masses. This 

 is probably produced by the goblet cells to be mentioned next. 



Intra-vitam methylen blue and various cytological prepara- 

 tions show that there are in Amia three main types of cells 

 i which have also been described by various workers on fishes) 

 in the Schneiderian membrane, viz., olfactory cells of various 

 shapes, ciliated supporting cells, and goblet cells secreting mucus. 

 The ciliated cells are most numerous, while the olfactory cells 

 come next in point of numbers. A ciliated supporting cell has 

 a larger surface on the cavity of the nasal capsule than an olfac- 

 tory cell. The mucous cells are isolated among the supporting 

 cells and can be readily recognized in preparations stained with 

 Delafield's hematoxylin. 



In the adult fish there are only one or two important changes 

 from the 50 mm. stage, in regard to the position of the ganglionic 

 cells of the nervus terminalis. Most of the cells come to lie in 

 the dorsal groove between the two main olfactory rami instead 

 of ventrally, as in the early stages (fig. 9). This position is 

 probably due to the increase of fibers in the lateral rami as the 

 surface of the nasal folds to be supplied increases in area. But 

 also, it may be that the cells migrate to a point nearer the place 

 to be innervated. There are slight variations in the position 

 of the cells in the adult. Sometimes a greater number of cells 

 are found ventrally of the olfactory nerve than in others. In 

 the adult there has ceased to be any decided ganglion at the 

 posterior end of the nasal capsule. There are a few more cells 

 posteriorly in the nasal capsule than farther rostrad, but the 

 surface of the folds and the number of blood vessels are greater 

 at the posterior end. The cells are nowhere aggregated in gan- 



