404 



THE NASAL REGION IN EUTAENIA. 



JVc, nc' . . Cartilage surrounding anterior nasal opening. 



Tr. . . Transverse plate of cartilage passing from the pedicle of the 



Organ of Jacobson to the turbinal cartilage. 



Unc. . . Upper nasal chamber. 



Lnc. . . Lower nasal chamber. 



Fig. 1. — A view of the roof of the mouth in Eutaenia sirtalis ; several times 

 magnified. 



Fig. 2. — A transverse section of the nasal region through the middle of the 

 Organ of Jacobson. x 20. 



Fig. 3. — One half of a transverse section of the nasal region through the 

 openings of the Organ of Jacobson and the lachrymal duct. 



x20. 



Fig. 4. — A transverse section some distance behind that represented in 

 Fig. 3. x 20. 



Fig. 5. — One half of a transverse section of the nasal region of an embryo 

 head 6 mm. in length of Eutaenia sirtalis. x 50. 



Fig. 6. — A transverse section of the nasal cavity anterior to the external 

 nasal opening. x 30. 



Fig. 7. — A transverse section of the nasal cavity containing the aperture 

 of the duct of Miiller's Nasal Gland. x 30 



Fig. 8. — A portion of a transverse section of Organ of Jacobson in an adult 

 Eutaenia ; ./. C. the canal of the Organ separating roof and floor ; 

 a, capillary vessel descending between columns, one of its 

 branches passing to the left around the point of passage of the 

 censory cells adjacent to superficial cells over into those of a 

 column. Separating the columns also is seen pigmentary tissue. 

 Above, the mucosa contains a nerve bundle cut across and a 

 large capillary. x 250 



Fig. 9. — A portion of the foregoing — a, superficial cells ; the peripheral pro- 

 cesses of the sensory cells pass down between them and through 

 the "border structure" ; b, sensory cells opposite a node (d) of 

 the capillary plexus ; c, those opposite a mesh of the same and 

 passing over into b' those of the columns. (The outer ends of 

 the sensory processes and of the superficial cells are represented 

 diagrammatically. ) x 700 



Fig. 10. — A transverse section of the posterior ends of the cellular columns 

 of the Organ of Jacobson in an embryo Entssnia. The plexus 

 separating the polygonal areas is not shown. x 200 



Fig. 11. — A longitudinal (diagrammatic) section of the lachrymal duct; a, 

 the basal portion found under the Organ of Jacobson and con- 

 tinued into b, ending blindly ; to the walls of this latter the 

 fused lachrymal cartilages are applied ; c, a swelling of the 

 lumen of the duct over the palatine bone ; d, the portion on a 

 level with turbinal. The gland is supposed to be seen through 

 the eyeball. 



Note— In the figures the shaded portions represent membrane bone, while the dotted pro- 

 tions are intended to designate cartillage. 



