296 TOKUYASU KUDO 
referred to may well be considered as the first anlage of the macula 
neglecta Retzii. In the wall of the canal there is no zone marked 
out by a cell-free border, although the epithelium is still rather 
thick, and this in turn is continuous with the mound-shaped 
swelling, the macula sacculi. 
Corresponding to the external changes in form, the macula 
partis inferioris is now separated into the papillae basilaris and 
lagenae, which are still united by cubical epithelium. The 
crista posterior is quite separated from the macula sacculi by an 
unspecialized epithelium. 
Stage 5. The embryo consists of 23 coils. The external 
characters are quite comparable to those of the preceding stage. 
Fixation: potassium bichromate. Stain: alcoholic borax car- 
mine. The 15 u sections are cut frontally through the head. 
The macula neglecta Retzii, which lies closely adjoining the 
canalis utriculo-saccularis, is mound-shaped and consists of two 
or three layers of cells. The maculae neglecta and sacculi are 
united by means of cubical epithelium except in the wall of the 
canal, where the epithelial cells are still tall. 
The Adult Animal (fig. 5). Fixation in potassium bichromate- 
acetic. Stain: haematoxylin-eosin and haematoxylin-orange G. 
The section are cut frontally through the head. 
Among the endorgans the cristae anterior and posterior are 
composed of two- to three-layered epithelium and project as 
rounded protuberances into the lumen. The macula utriculi 
lies on the anterior-medial wall of the utriculus and is composed 
of auditory and supporting cells. The macula neglecta appears 
as a swelling in the proximity of the canalis utriculo-saccularis 
on the floor of the utriculus; its vesicular auditory cells rest upon 
one or two layers of supporting cells. The macula diminishes 
in thickness as it passes over into the simple cylindrical epithe- 
lium which makes up the wall of the canal and which is continued 
beyond in the wall of the sacculus. The tall epithelium found 
on the medial wall of the canal is also to be seen on and near the 
lateral wall. In several places within and near the canal the 
lining is thrown up into wave-like folds. 
