Ixxvi Journal of Comparative Neurology. 



optic radiations which connect those centres of the di- and mesencepha- 

 lon with the occipital cortex. I propose to call these tracts passing 

 caudad from the olfactory bulbs olfactory radiations. 



The psychical processes of olfactory sensation may be referred 

 with considerable certainty in mammals to the gyrus arcuatus and par- 

 ticularly its caudal region including the regio ammonis. If it is pos- 

 sible to show that the first cortex to appear is really Ammons' cortex 

 it becomes extraordinarily probable that the first psychical function 

 of cortical nature corresponds to the appreciation of olfactory sensa- 

 tions." 



[The reader is referred to a discussion of these questions in vol- 

 ume II of this Journal, p. 2-7, in which a similar view is taken re- 

 specting the independence of the pero of the olfactory tuber from the 

 cortex. It was there shown that the so-called olfactory branch of the 

 praecommissura is not connected with the pero. 



The radix pedis lateralis is there described as passing caudad 

 along the fissura radicis to the pyriform lobe, thence for the most 

 part to cross mesad and entad into the hippocampus. In Bulletin of 

 Denison University VI, C. Judson Herrick confirms this statement. 

 In the first paper above quoted it is suggested that the olfactory gang- 

 lion may have fused with the brain forming an apparent organic unity 

 and that the adhesion of the pero to the pes is a comparatively sub- 

 ordinate character.] 



Dr. Edinger agrees with the writer that the cortex of reptiles is 

 connected with the olfactory tubers by strong tracts and also makes 

 the suggestion that the concentrically rolled part of the axial lobe (his 

 "nucleus sphaericus " — our " occipito basal lobe ") is directly con- 

 tinuous with the hippocampal cortex and is to be regardedas an in- 

 rolled part of it. 



This view is remarkably similar to the suggestion made in 1890^ 

 and subsequently that the caudal part of the axial lobe is a proliferat- 

 ing area from which there is increase of the mantle " as though the 

 material were pushed up around the margins of the ventricle by a 

 rapid growth within." 



In the turtle Dr. Edinger finds the olfactory composed of the 

 root bundles of the olfactory arising from the epithelium of the nasal 

 cavity and which subdivide in the glomerules, of the central cells of 

 the bulb which send their processes to the bulb, and of a portion passing 

 caudad, which in part consists of processes and axis cylinders of these 



^ Notes on the Brain of the Alligator. 



