and 3 
lerm; 
‘ough 
and 6 
ıents. 
1ence 
at of 
ıllary 
r end 
; and 
terior 
brupt 
roove 
allow 
a 
derm 
row. 
etely 
stinct 
a ————— 
Normentafel of the development of the rabbit (Lepus cuniculus L.). 
ee ————— 
17 
Eye 
Nose and Mouth 
Hypophysis and Infundibulum 
Anlagen of optic vesicles in lateral parts of 
cephalic end of raised medullary plate? 
A little expansion of cephalic end of medullary 
plate. Essentially the same condition as in No. 650, 
Table 1. 
Essentially the same condition as in No. 621, 
Table 4. 
Primary optic vesicles distinct, though small; open 
widely into medullary tube, which is open dor- 
sally. They form the entire lateral boundary of 
medullary tube at point of connection. Ventral 
wall of vesicle thicker than dorsal. 
Optic vesicles a little more expanded than in 
No. 62I, Table 4. 
Optic vesicles larger than in No. 620. Anterior 
portion of optic vesicle wide open to region of 
fore-brain, the complete lateral boundary of which 
it forms. Posterior portion of optic vesicle ventral 
in connection with fore-brain. 
Essentially like No. 619, Table 6. 
Optic stalk in process of differentiation. A little 
mesoderm between lateral wall of optic vesicle | 
and external ectoderm. 
Optic stalk very short; .distinctly ventral in con- 
nection with fore-brain. Optic vesicles somewhat 
expanded laterally, extend a little caudad of optic 
stalk. A little mesoderm between lateral wall 
of optic vesicle and external ectoderm. 
Primary optic vesicle in essentially the same 
condition as at 9'/, days. 
Optic stalk a little longer than at Io days; con- 
nects with ventral region of fore-brain. Very 
slight thickening of external ectoderm forming 
lens anlage. 
Slight thickening of lens anlage a little invagi- 
nated. Outer wall of optic vesicle flattened, a 
little thickened, indicating retinal anlage. The 
latter closely approximated to the anlage of lens. 
Optic stalk short, hollow. 
Lentic cup connected with external ectoderm and 
open to exterior by a narrow mouth only. Inner 
wall of cup slightly thickened. Secondary optic | 
cup clearly formed by invagination of retinal 
anlage. Cavity of primary optic vesicle very 
small. Beginning of choroid fissure, invagination 
of ventral side of optic cup. Short, hollow optic 
stalk. Small blood vessel in narrow space between 
inner wall of lentic cup and retinal anlage. 
Essentially the same condition as in Ir’), day 
embryos. In one I2 day (5.0 mm) series, lentic 
vesicle is completely closed and separated from 
external ectoderm. 
Very early anlage of otocyst, | 
a slight thickening of ectoderm, 
quite level, lateral to hind-brain. 
Anlage of otocyst, a slight | 
thickening of ectoderm, nearly 
level, close against wall of 
hind-brain. Anlage of acoustico- 
facial ganglion lies ventral and 
cephalad. 
Anlage of otocyst slightly con- 
cave dorsally. 
Otocyst anlage concave dor- | 
sally forming small open cup. 
Acoustico-facial ganglion lies | 
ventral to cephalic end of 
otocyst. 
Otocyst closed but connected 
with dorsal ectoderm. Otocyst 
lies close against wall of hind- 
brain. 
A trace of connection of oto- 
cyst with dorsal ectoderm. Oto- 
cyst circular in cross section. 
In one ıo day (3.0 mm) series 
otocyst is open. 
A trace of former connection 
of otocyst with dorsal ecto- 
derm, but no actual connection. 
Cephalic portion of otocyst lies 
close against wall of hind-brain. 
Distinet beginning of ductus 
endolymphaticus, which is short. 
Cephalic wall of otocyst joined 
to acoustico-facial ganglion. 
Otocyst, roughly somewhat 
triangular in dorso-ventral sec- 
tion, separated from wall of 
hind-brain by narrow strip of 
mesenchyma. Acoustico-facial 
ganglion close against anterior 
wall of otocyst. 
as at ıı!/, days. 
Short ductus endolymphaticus. | 
Essentially the same condition | 
Normentafeln zur Entwicklungsgeschichte der Wirbelthiere. V. 
Entoderm of fore-gut in contact with 
| ectoderm. 
Entoderm 
ectoderm. 
of fore-gut in contact with 
Entoderm 
ectoderm. 
of fore-gut in contact with 
Oral membrane. Entoderm of fore-gut 
joined to ectoderm. 
Oral membrane formed; entoderm of 
fore-gut joined to ectoderm. Small oral 
cavity. 
Oral membrane distinet, a solid epi- 
thelial band. Small oral cavity. 
Oral membrane in part broken through. 
Oral cavity deeper than in No. 623; 
more distinct; in median line bounded 
above by head, below by pericardial 
| wall; laterally mandibular arches inter 
pose. The latter quite prominent; maxil- 
lary processes very small. 
Fore-gut wide open to mouth cavity; 
caudal portions of mandibular arches 
joined together in median line. On one 
ıo day (3.0 mm) series the oral mem- 
brane is intact. 
Olfactory plates, slight ectodermalthicke- 
nings, level, of considerable extent. Oral | 
cavity wide open between maxillary pro- 
cesses; open also at cephalic border of 
mandibular processes. Caudal portions 
of mandibular processes meet in median | 
line. 
Hypophysis a very small evagination 
of ectoderm on dorsal side of mouth 
cavity just in front of oral plate, 
which is broken through in middle. 
brain. 
Hypophysis very small, essentially 
the same as at 9!/, days. 
Diverticulum of hypophysis well 
marked, larger than at ıo days, rather 
foursided in cross section, closely 
|approximated to wall of fore-brain. 
| 
Olfactory plates, slight ectodermalthicke- | Hypophysis a little longer than at 
nings, for the most part level; the pos- 
terior parts of plates a little bent in, 
concave to exterior. 
between maxillary and mandibular pro- 
cesses. 
Shallow nasal pits. 1 
mouth cavity communicates widely with 
pharynx. 
Nasal pits shallow. Very early indi- 
cation of JACOBSON’S organ. 
Oral cavity open| 
ı0'/, days. Upper end closely joined 
to wall of fore-brain. 
| 
In median plane |Hypophysis quite long, closely ap- 
|proximated to floor of fore-brain. | 
Upper end of hypophysis flattened 
| dorso-ventrally. 
Infundibulum present as a very small 
|evagination of floor of fore-brain. 
Upper end of hypophysis slightly 
expanded laterally, slightly concave 
toward fore-brain, joined to infundi- 
bulum. 
3 
Hypophysis close against wall ot fore- 
I} 
| 
| 
n 
| 
| 
