228 J. B. JOHNSTON, 
not appear that this memory is necessarily. dependent on the fore 
brain, since in STEINER’s fish all functions seemed to be intact ex- 
cept the olfactory sense and its influence on the motor reactions. 
It would be interesting to perform similar experiments with STEINER’s 
operated fish. 
b) The olfactory Apparatus. 
1. The olfactory Lobe. 
The nerve elements in the lobe have been studied by the GoLer 
method in fishes by VAN GEHUCHTEN (94), SAUERBECK (96) and 
F. MAYER (97), in Amphibia by BERDEZ (93) and P. Ramon (94), 
in Reptiles by CALLEJA (93), P. Ramon (91), LÖWENTHAL (94) and 
EDINGER (96), in birds by P. Ramon (90), in Mammals by Gouer 
(75), S. Ramon (90), VAN GEHUCHTEN & MARTIN (91), ConıL (92), 
Rerzıus (92), KÖLLIKER (91 and ’96), and Monti (95). 
In fishes VAN GEHUCHTEN figures the endings of a few ol- 
factory fibres. SAUERBECK mentions the impregnation of a few 
mitral cells in his preparations of the Selachian brain. F. MAYER 
(97) describes the olfactory lobe in Ammocoetes as follows: “An 
dem Aufbau der Glomeruli olfactorii betheiligen sich ausser der Auf- 
splitterung je einer Riechnervenfaser, sowie einer oder mehrerer 
Mitralzellen, auch die Verästelungen der den Ventrikel bekleidenden 
Ependymzellen. Alle drei Bestandtheile bilden ein dichtes Faser- 
werk, in welchem die Nerven frei, mit feinen, külbchenartigen An- 
schwellungen endigen. Nach innen von den Glomeruli folgt eine 
breite Schicht, welche die Mitralzellen, Nervenfasern, sowie Ependym- 
zellen enthält. Ausser den Mitralzellen, welche unter einander keine 
bedeutenden Verschiedenheiten zeigen, besitzt der Lobus olfactorius 
keinerlei Ganglienzellen.” The fibre layer contains two kinds of 
fibres, the neurites of mitral cells running to the “cortex”, and fibres 
coming from the commissura superior, being neurites of cells in the 
thalamus and hypothalamus. 
P. Ramon (94) gives an excellent detailed description of the 
olfactory lobe of Rana. The superficial zone of olfactory fibres con- 
tains occasional small nerve cells which are comparable to the small 
mitral cells of Mammals. Beneath this zone are the olfactory 
glomeruli, each of which receives a variable number of peripheral 
fibres. The mitral cells are distributed without orderly arrangement 
in the glomerular zone. Each mitral cell has several widely ex- 
