Literary Notices. xix 



other. Callosal fibres have developed along some pre-existing route of 

 connection and then attained their present position in obedience to the 

 usual laws of developmental adjustment. Smith says that the fibres 

 "probably belong to the lamina infra-neuroporica and supersede the 

 cephalic part of the fornix commissure whose position they usurp." 

 "The corresponding region of the hippocampus [in higher mammals] 

 disappears and the supracallosal gyrus of Zuckerkandl is all that re- 

 mains of this region in the Eutherian brain." 



If this suggestion as to the origin of the callosal fibres could in 

 any way be verified the last serious obscurity in this problem would 

 seem to be solved. 



In a still more recent paper on " Jacobson's Organ and the Olfac- 

 tory Bulb in Ornithorhynchus"^ the same author corrects some very 

 serious blunders in Dr. Hill's paper in the Philos. Trans. 1893, whose 

 specimen had the bulb artificially disconnected and rotated through 45 

 degrees. The author finds the same olfactory fossa which we have 

 called attention to in Reptilia and opossum and verifies its relation to 

 Jacobson's organ. In Platypus it is much deeper than even in the 

 black snake but is on the dorso-lateral rather than mesal aspect. A 

 study of the relations of the part of the olfactory bulb associated with 

 Jacobson's organ does not reveal any arrangement different from the 

 rest of the bulb. It would appear that in all its connections with the 

 brain the organ of Jacobson exactly resembles the olfactory apparatus 

 proper and like the latter has its centres in the pyriform lobe and prob- 

 ably also in the hippocampus. c. L. H. 



Fibre Connections of tlie Olfactory Lobe of Man.^ 



It will be recalled that recent investigators have shown by a variety 

 of methods that the connections of the olfactory nerve in the olfactory 

 lobe are practically the same in all vertebrates, the peripheral nerve 

 forming a terminal arborization in the glomerule, there to enter into 

 relations with the protoplasmic process of one or more of the mitral 

 cells of the olfactory lobe whose axis cylinders effect the cortical con- 

 nections. In batrachians, reptiles and birds each mitral cell gives off 

 more than one protoplasmic process and thus is related to more than 

 one glomerule. No mammal hitherto studied has shown this arrange- 

 ment, there being but one protoplasmic process to each mitral cell. In 



> Anat. Am., XI, 6. 



^Gehuchten, a. van. Le bulbe olfactif de rhomme. Bibliog. Anatomique, 

 III, 4, Aug., 1895. 



