18 
Normentafeln zur Entwicklungsgeschichte der 
Wirbelthiere. 
u nn nen 
Pharynx. Thyroid. Thymus 
| Digestive Tract. Liver. Pancreas. 
Spleen 
Respiratory Tract 
Urogenital System 
First entodermal gill pouch formed: ento- 
derm of pharynx meets external ecto- 
derm. 
First entodermal gill pouch; entoderm 
of pharynx meets ectoderm. Beginning 
of second entodermal pouch. 
Closing membrane of first entodermal 
pouch formed. Second entodermal gill, 
pouch: entoderm touches ectoderm. 
First gill pouch with closing membrane. 
Second gill pouch: entoderm touches 
ectoderm. Mandibular arch indicated. 
Closing membranes of first and second 
entodermal pouches clearly formed. 
Third gill pouch distinet: entoderm 
touches ectoderm. Mandibular and hyoid | 
arches distinct. Maxillary process slightly 
indicated. Median thyroid anlage, a small 
solid median entodermal thickening, pro- 
|jecting ventrad from pharynx. 
Closing membranes of first and second 
gill pouches. Third gill pouch distinct; 
| entoderm joined to ectoderm. Maxillary 
process, mandibular and hyoid arches 
distinct. Small solid median thyroid an- 
lage, projecting ventrad from pharynx. 
Beginning of cervical sinus. Closing | 
membranes of first, second and third 
entodermal gill pouches. Small fourth 
gill pouch; its entoderm separated from 
external ectoderm by mesoderm. Small 
solid median thyroid anlage. Early| 
thymus anlagen, small evaginations ven- 
Fore-gut extends through 13 sections of 10 u». 
Beginning of hind-gut. Anal membrane formed; 
entoderm in contact with ectoderm. 
Fore-gut extends through 13 sections of 6 u. 
In essentially the same condition as No. 571, 
Table 3. 
Fore-gut extends through 45 sections of 6 u. 
Beginning of hind-gut. Anal membrane. 
Fore-gut extends through 54 sections of 6 u; 
hind-gut through 13 sections of 6 u. Anal 
membrane. 
Fore-gut extends through 60 sections of 8 u; 
hind-gut through 24 sections of 8 u. Anal 
membrane. 
Fore-gut extends through 65 sections of 8 u; 
hind-gut through 37 sections of 8 u. Mid-gut 
open to yolk sack through 120 sections of 
8 u. Anal membrane ventral. 
Liver anlage consists of a tubular outpocketing 
from intestine. To this outpocketing is attached 
a small, solid mass of cells, lying in septum 
transversum. Early anlage of stomach as slight 
expansion of gut, straight? Cloaca somewhat 
differentiated. Anal membrane. Post-anal gut 
not clearly formed. 
Anlage of stomach indicated. Liver anlage 
in essentially the same condition as at 9!/, days. 
Opening of gut into yolk sack quite wide 
Cloaca distinct. Small anal membrane. Post- 
anal gut scarcely formed. 
Anlage of stomach distinct. Solid cell masses 
of liver anlage in septum transversum. Opening 
of gut into yolk sack small. Anal membrane. 
Post-anal gut scarcely formed. 
|trad from lateral ends of third gill| 
pouches. | 
Closing membranes of first, second E 
third gill pouches. Fourth gill pouch | 
small; its entoderm separated from ecto- 
| derm by mesoderm. Small solid median 
|thyroid anlage joined to entoderm of 
| pharynx in region of second gill arches. 
Thymus anlagen, ventrad projections 
from 3rd pouches. 3rd and Ath gill arches 
included in cervical sinus. 
| Closing membranes of first, second and 
|third gill pouches. Fourth gill pouch 
small; its entoderm separated from ecto- 
derm. Small solid median thyroid anlage. 
Thymus anlagen, tubular ventrad pro- 
jections from third gill pouch. Anlagen 
of lateral thyroids, small projections from 
fourth gill pouch. 
Essentially like ı1!/, day embryos. 
 Distinct cloaca. Anal membrane. Distinct but 
Stomach turned to left. Solid cords of liver 
cells irregularly arranged in septum trans- 
versum; very vascular. Dorsal pancreas small. 
short post-anal gut. 
Cavity of caudal part of oesophagus very 
narrow. Stomach well marked, turned deci- 
dedly to left. Lesser peritoneal cavity closed 
cephalad. Very vascular network ofsolid cords 
of liver cells. Division of liver into lobes indi- 
cated. Anlage of gall bladder distinct. Dorsal 
pancreas distinct. Early indication of ventral 
pancreas. Gut bends toward navel. Yolk stalk 
in umbilicus has very small cavity. Anal mem- 
brane. Post-anal gut with small cavity. 
Pulmonary groove 
out. 
Pulmonary groove 
narrow:openthrough- 
out. 
Pulmonary groove 
narrow, elongated 
dorso-ventrally, open 
throughout. Slight 
expansion of ventral 
portion of pulmonary 
groove, early indi- 
cation of pulmonary 
outgrowths. 
Pulmonary groove 
open throughout. 
Small pulmonary an- 
lagen, right and left. 
Considerable mes- 
enchyma about latter. 
Caudad, anlage of 
trachea completely 
separated from .oeso- 
phagus by mes- 
enchyma; cephalad, 
pulmonary groove 
open to oesophagus. 
Rıght and left primary 
bronchi. 
present: openthrough- 
Beginning of Wolffian duct (?) as a small 
solid cell accumulation on dorsal side of 
nephrotome and connected with it in region 
of posterior segments; of very short extent. 
A similar structure to that described in 
No. 571, Table 3 but somewhat more dis- 
tinct. 
Distinct solid anlage of Wolffian duct on 
dorsal side of intermediate cell mass and 
attached to latter; in region of median 
segments, approximately. Longer than be- 
fore but still rather short. 
Essentially the same condition as in No. 619, 
Table 6. 
Large solid anlage of Wolffian duct in region 
of posterior segments. Caudal end of Wolf- 
fian duct has a connection with ectoderm. 
Solid Wolffian duct imbedded in mes- 
enchyma, situated in trunk of body. Wolf- 
fian duct apparently ends blindly in posterior 
part of trunk, without any connection either 
with ectoderm or with cloacal epithelium. 
Beginning of Wolffian tubule? 
Wolffian duct shows trace of lumen. Blind 
cephalic end of Wolffian duct close against 
coelomic epithelium or joined to it. Wolf- 
fian duct joined to epithelium of cloaca but 
without any opening. Small Wolffian tubules 
with small lumina. A tubule joined to Wolf- 
fian duct and to coelomic epithelium. 
Numerous Wolffian tubules showing traces 
duct, which. has a small lumen. Epithelium 
of Wolffian duct fuses with epithelium ot 
cloaca, apparently without any opening. 
Numerous Wolffian tubules with small ca- 
vities. Cavity of Wolffian tubule communi- 
cates with cavity of Wolffian duct. Wolffian 
tubule bent S-shaped. Cephalad Wolffian 
duct ends blindly; caudad it fuses with 
cloaca but without opening through. 
In region of liver and stomach, a small cell 
structure dorsal to coelom, showing in part 
traces of a lumen, with solid connecting 
band to coelomic epithelium; corresponding 
in position to that of Wolffian duct or 
tubule but well cephalad of Wolffian duct. 
Wolffian duct now opens into cloaca. Very 
short beginning of ureter on dorsal side of 
Wolffian duct. Beginning glomerulus for- 
mation. 
Blind cephalic end of Wolffian duct close 
against coelomic epithelium in region of 
fore limbs. Wolffian tubules extend to 
region of hind limbs. Wolffian duct opens 
freely into cloaca. Ureter a little longer 
than at ı1!/, days. 
of lumina; they are connected with Wolffian ' 
\ 
a a ee ee een 
