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olfactory nervefibres; the fundamental substance in which these nuclei 
are imbedded deeply stains with eosine. Where these fibres leave 
the brain, the superficial layer of the hemisphere vesicle becomes 
richer in elongated nuclei (A vn. fig. I, II, HI, IV and VI). They 
form four bundles (Rd. N. vn. tig. Ill, IV and VI), which all 
converge into the ganglion olfactorium (G. vn. fig. HI, IV, VI). The 
nerves leaving this ganglion are arranged in five bundles (Fig. VI 
Nn. vn) which all went to the mesial side along the cartilagineous 
septum nasi (Fig. 1 Sp.m.n.). Unfortunately the course of these nerves 
could be no further traced out, the head being cut off too close along 
the base of the brain. In a second human embryo however, of the 
same age, which was not so well preserved, it was possible to find 
back the same relations and to see, that all these nervefibres run 
exclusively to the organon vomeronasale (RuyscH, Jacopson). In the 
whole course of these nerves ganglioncells are seen. The so called 
ganglion olfactorium has therefore no connection with the olfactory 
nervefibres but is the sensorial ganglion belonging to the organon 
vomeronasale. 
In figure VI is given a semidiagrammatic drawing constructed 
from the sections where the whole apparatus belonging to the organon 
vomeronasale is projected upon a sagittal plane. The ganglion vomero- 
nasale (G. vn.) is seen in the niveau of the top of the olfactory bulb 
from which proceed to the periphery the nervi vomeronasales (Nn. 
Vn.) and to the centrum the so called internal olfactory roots (Rd. N. vn.). 
which enter the brain in a large triangleshaped zone, the area 
vomeronasalis (A. vn.) 
In the guinea pig these relations are slightly different. From the 
organon vomeronasale proceed two nervestrands, which at a short 
distance and still in the submucosa of the nose have each a ganglion. 
This paired ganglion vomeronasale has two roots which very soon 
unite and intermingle with the nervi olfactorii, with which they 
perforate the lamina cribrosa. Arrived at the base of the brain they 
enter the olfactory bulb over a large area, reaching from the sulcus 
circularis bulbi at the mesial side to some distance from the same 
sulcus at the lateral side of the olfactory bulb. 
Probably the same relations occur through the whole series of 
vertebrate animals. Though the existence of an organon vomeronasale 
can be doubted in anamnia, it seems very probable, that the 
nerve described by Locy (Anat. Anz. 1905, Heft 2 and 3) in 
Selachii is identical with the nerve of the organon vomeronasale 
as described here. 
From the preceding description it is obvious, that we have 
