504 WILLIAM H. F. ADDISON 
small, and the olfactory peduncle or tract narrow but very 
elongated. As Elliot Smith (’02) points out, the length of the 
peduncle in the human brain is probably brought about by the 
bulb being anchored in a fixed position by the olfactory nerves 
coming through the cribriform plate, and by the increase in size 
of the frontal lobe, which moves backward the position of the 
attachment of the peduncle to the base of the brain. These two 
circumstances result in the great attenuation of the peduncle. 
The lobus parolfactorius in the calf (fig. 2) shows an appear- 
ance typical for many macrosmatic animals, as found by Beccari 
(10). In man this region is so reduced as to make the term 
eminentia parolfactoria more appropriate. According to Bec- 
cari (’11) who investigated a series of fifty human brains, in 
twenty-five per cent (25%) it was well developed, in fifty per 
cent (50%) weakly developed, and in twenty-five per cent (25%) 
was lacking. This region has been the subject of recent contro- 
versy. Edinger has wished to separate it from the olfactory 
system, and asserts that but few olfactory fibers (e.g. of tractus 
olfacto-corticalis) penetrate it, but that it receives tracts from 
the region where the trigeminus ends. The lobus parolfactor- 
ius he would designate as the center for impulses, coming by way 
of the fifth nerve, from specialized sensory structures in the 
snout region. Its variation in size in the different species he 
would correlate not with the olfactory sense but with the ‘oral 
sense,’ the height of development of which depends upon the size 
and character of the innervated area at the oral pole. Elliot 
Smith, using the brain of Orycteropus, contended that many 
fibers of the olfactory tracts could be seen covering and entering 
this lobe and hence that it should still be called tuberculum 
olfactorium. Later Edinger studied sections of the brain of 
Orycteropus and found that this lobe received none or very few 
of the olfactory fibers. The region was examined carefully by | 
Beccari (710, ’11) in a series of mammals and in man, and he 
agrees with Edinger that it is a special field, but does not think 
the proof quite sufficient that it has to do with an oral sense. He 
found that it has well developed connections with the hippo- 
campus, nucleus amygdalae, and ganglion habenulae, slighter 
