Bawden, Nose and Jacobsons Organ. 139 



numerous small glands which seem to have their openings in 

 the interspaces of the crypts. (Fig. 1, gla, Plate IX). This 

 arrangement is seen in Fig. 6, Plate VI, in cross section, and 

 in Fig. 1, Plate VII, longitudinal section. See also Fig. 2, 

 Plate VII, epi. 



The model of Amblystoma shows also transverse and lon- 

 gitudinal sections of the nerve-bundles supplying the olfactory 

 cavity. They are shown on the model cut off obliquely as they 

 enter the olfactory bulb. (Fig. 4, Plate XII, and in section, Fig. 

 6, Plate VI, en and In.) Fig. 1, Plate X, obi, represents the 

 innervation of the nasal epithelium of the tadpole showing the 

 nerve-bundle as it originates in the olfactory bulb. 



The innervation and histology of facobson s organ is in gen- 

 eral comparable to that of the nose proper. With regard to the 

 innervation of Jacobson's organ it is probable that the division 

 of the olfactory nerve into two branches is not as Wiedersheim 

 and Marshall formerly believed, homologous with the two 

 branches of a cranial nerve to each side of a gill-cleft, but a 

 division into two bundles passing respectively to the nose proper 

 and Jacobson's organ, and where no diverticle is present, com- 

 pletely homologous with the similar division where it is present 

 (as in the Reptilia). 



The sensory epithelium of Jacobson's diverticle in Gym- 

 nophiona, says Burkhardt, remains as in the embryonic condition 

 without any tendency to form sensory buds as in the olfactory 

 proper, which indicates a retardation as compared with the nasal 

 epithelium. 



In Amphibia in general the nerve-bundle for Jacobson di- 

 verticle passes to a little pit (the olfactory fossa) on the olfactory 

 tuber with connections to the radix lateralis, as in Reptilia. The 

 olfactory nerve of tailed Amphibia (salamander) corresponds in 

 its relations to the cerebrum, decidedly, to the lower branches of 

 the olfactory nerve of frog larvae and Gymnophiona. 



Beard, speaking of its histology in Reptilia, finds the nerve- 

 fibres ending in the bases of the ganglionic columns which lie 

 just within the true epithelium cells. He says distinctly that 

 the nerve-fibres do not pass between the columns or crypts, but 



