298 TOKUYASU KUDO 
sacculi nach aufwirts zum Foramen Utr.-Sace., wo es zu einer 
zweiten Neuroepithelstelle—2) Macula neglecta Sarasinian- 
schwillt, die im Foramen Utr.- sacc. (an dessen hinterem Rand) 
gelegen, zum kleineren Teil in den Sacculus, zum grésseren in 
den Utriculus hineinragt. Von dieser erstreckt sich wieder ein 
niedriges Epithel in den Sinus inferior hinein zu persistierenden 
3) Macula neglecta (Retzii). Beide Maculae neglectae stehen 
auf derselben Entwicklungsstufe.”’ 
Now even if the bulging endorgan found in the floor of the utric- 
ulus of stages 4 and 5 were not to be regarded as the macula 
neglecta Sarasini but rather as the macula neglecta Retzii, | would 
not feel justified in interpreting the thickened epithelium which 
extends through the canalis utriculo-saccularis to the macula sac- 
cularis as the macula Sarasini. The further the development 
progresses the thinner does the epithelium of the inner wall of the 
alveus become as compared with the early stage of the auditory 
vesicle. One may readily see that the medial wall of the alveus 
communis is lined with relatively taller epithelial cells in stage 
2 than in stage 3. From this it is apparent that the neuroepi- 
thelium, except where it progressively develops into nerve endor- 
gans, is destined to be reduced to indifferent epithelium, even 
though the time when it retrogresses be very variable. 
According to my opinion, therefore, the tall epithelium of 
medial wall of the canal and its proximity represents a develop- 
mental stage in the neuroepithelium which later retrogresses. 
If this epithelium were to be interpreted as a nerve endorgan, the 
tall epithelium of other regions, as e.g., of the lateral wall] of the 
canal and the medial wall of the utriculus and the ductus endo- 
lymphaticus, would have to be regarded as neuroepithelium, since 
these latter regions are quite similar in structure and arrangement 
of their epithelial cells to those in the medial wall of the canal. 
At any rate, the macula neglecta does not occur in my material 
as it has been pictured by Fleissig in his work. But it should be 
noted that in the adult snake the epithelium of the canalis 
utriculo-saccularis and its immediate environs is relatively much 
thicker as compared with the medial and lateral walls. 
