3lind 
ainst 
Volf- 
ı but 
Jules 
Volf- 
Normentafel of the development of the rabbit (Lepus cuniculis L.). 
——zpsan a gps 
19 
Heart and Blood Vessels 
Integument 
Extremities 
Amnion 
Allantois 
A few small solid blood anlagen over yolk sack. Embryonic coelom 
begun, more advanced in future heart region. 
Blood vessels with primitive blood cells over yolk sack. Blood anlagen 
over yolk sack partly solid. Double lateral heart anlage (vitelline veins) 
endothelial tube and mesothelial projection. No single median heart. Primi- 
tive dorsal aortae in segmented region. Pericardial coelom well formed. 
Over yolk sack, blood vessels; primitive blood cells; partly solid blood 
anlagen. Lateral heart anlagen beginning to bend ventrad; nowhere 
united into a single heart Distinct primitive dorsal aortae. First aortic 
arch apparently formed. No blood cells in heart anlagen, nor in dorsal 
aortae. 
Blood anlagen over yolk sack partly solid. Double heart anlage ventral 
to fore-gut but nowhere united to a single heart. Distinct dorsal aortae. 
First aortic arch. Dorsal aorta contains a few primitive blood cells. 
Single median heart. Embryonic coelom closed by projection of vitelline 
vein at entrance of latter into embryo. Heart tube bent a little to the 
right. Venous and aortic end of heart differentiated. First aortic arch. 
Anterior cardinal (jugular) vein appearing. Umbilical vein appears, contains 
blood cells. Dorsal aortae contain a few blood cells. No blood cells in 
heart. 
Umbilical veins communicate with vitelline. At point of communication, 
coelom is bridged. Large sinus venosus. Auricular region, ventricular and 
aortic limbs of heart indicated. Heart bent somewhat S-shaped; contains 
blood cells. First aortic arches. Anterior cardinal veins present. Umbilical 
veins distinet. Dorsal aortae large, containing blood cells. 
Sinus venosus. Auricular region of heart single. Heart bent somewhat 
S-shaped. Aortic limb distinct. First aortic arch. Second aortic arch 
distinet. Two ventral carotids. Anterior cardinal (jugular) veins distinct. 
Umbilical veins; posterior cardinal veins distinet. Two dorsal aortae fuse 
into one at about middle of trunk. Well caudad, again two dorsal aortae. 
Allantoic arteries distinct, quite large. (Beginning of septum transversum.) 
Vitelline veins on each side of embryonic intestine in region of yolk stalk. 
Umbilical veins open into vitelline, on respective sides. Short ducts of 
CUVIER. Sinus venosus. Auricular region of heart expanded but without 
division. Ventricular wall thicker than auricular. Heart bent S-shaped. 
First, second and third aortic arches; the second, large vessels. Dorsal 
and ventral carotids distinct? Jugular veins large. Posterior cardinal veins 
quite large. Two dorsal aortae fused in region of fore limbs; again 
double in caudal part of body. Two large umbilical arteries. 
„ Vitelline veins enter embryo along yolk stalk. Short ducts of CUVIER. 
“ Regions of right and left auricles of heart indicated, but no internal di- 
vision. Beginning trabeculae in ventricular wall of heart. The two first 
connecting aorticarches have disappeard. Ventral carotids. Dorsal (internal) 
carotids quite large. Second, third and fourth aortic arches; the latter two 
pairs small. Jugular vein, quite large, passes internal to 5 ganglion, external 
to 7 and 8 ganglion. Two dorsal aortae fused a little cephalad of fore 
limbs; again divided in region of hind limbs. Right umbilical vein a little 
larger than left, both large vessels; they communicate in umbilical cord. 
A connection between vitelline veins dorsal to intestine; another ventral 
to intestine. Vitelline veins pass through liver, in which they communicate 
and are broken up. Umbilical veins open into vitelline in liver. Short 
ducts of CUVIER opening into sinus venosus. Small beginning septum 
primum in auricles of heart. Distinct truncus arteriosus. Second connecting 
aortic arch complete, though divided into small vessels. Third, fourth and 
fifth aortic arches. Right and left pulmonary arteries very small. Dorsal 
aortae fused in region of pulmonary anlage; single dorsal aorta to a point 
just caudad of hind limbs. Left umbilical vein larger than right. 
Left vitelline artery. A large single vein with irregular course, derived 
from vitellines. Umbilical veins enter liver. Right duct of CUVIER opens 
into sinus venosus. Left duct present. Auriculo-ventricular canal small, 
undivided. Truncus arteriosus undivided. Pulmonary arteries small. Third, 
fourth and fifth aortic arches; the fourth arches large. The second con- 
necting aortic arches have disappeared as distincet vessels. Two aortae | 
fused in region of pulmonary anlage. Large umbilical arteries. 
Ectoderm ad- 
joining medul- 
lary plate one- 
layered. 
Same as 
No. 650, 
Table ı. 
Embryonic 
een ad- 
joining medul- 
lary tube one- 
layered. 
Same as 
No. 571, 
Table 3. 
Same as 
No. 621, 
Table 4. 
Same as 
No. 620, 
Table 5. 
Embryonic 
ectoderm one- 
layered. 
Same as at 
9 days. 
Same as 
No. 623, 
Table 8. 
Apparently very 
slight evidences of | 
fore and hind limb 
buds; merely small 
swellings of body 
wall. 
Very small swel- 
lings of body wall 
indicating fore and | 
hind limb buds. | 
Fore limb buds dis- 
tinct as small pro- 
jections from body 
wall. Hind limb 
buds the same, ex- 
cept apparently a 
little smaller than 
fore limbs. 
Fore limb buds 
make more distinct 
projections of vas- 
cular, somewhat 
condensed meso- 
derm. Hind limbs | 
about the same. 
Fore limb buds a 
little larger, some- 
what flattened on 
end. Hind limbs 
about the same. 
Like No. 571, Table 3. 
No amniotic folds in this em- 
bryo. 
Caudal amniotic fold closed 
over extreme posterior end of| 
primitive streak region. Pro- 
amniotic area. No head fold. 
Caudal amnion closed over pos- 
|terior part of primitive streak 
region. Head sunk in proamnion 
to level of edges of latter. 
Dorsal surface of head sunk, 
to level of edges of folds of| 
proamnion. Lateral amniotic | 
folds in region of open posterior | 
partofmedullary groove, caudal | 
amnion closed over latter. | 
Head below level of extra-em- 
bryonic disk. Proamnion closed | 
closed over posterior part of em- 
bryo for some distance. Small | 
lateralamniotic folds, wideopen. | 
Caudal amnion closed to a 
point dorsal to segments. 
| 
. . | 
Head enclosed in proamnion. | 
cleft in heart region. Amnion 
closed from a point dorsal to 
anterior segments caudad. 
Amnion closed. 
|No entodermal al-ı 
overtipofhead. Caudalamnion | mal allantoic fold. 
|mal allantois just, 
| beginning. | 
No entodermal al-ı 
lantois. Beginning 
of mesodermal al-| 
lantoic fold ? 
Like No. 621, 
Table 4. 
lantois. Mesoder- | 
| mal allantoic fold? | 
No entodermal al- 
lantois. Small me- 
sodermal allantoic | 
fold. 
No entodermal al- | 
lantois. Mesoder- | 
Mesodermal allan- | 
|toic fold larger; in | 
| part ventral to | 
hind-gut. Entoder- | 
Thick mesodermal | 
Amnion open only by anarrow |allantoic fold ven-| 
tral to hind-gut. 
Entodermal allan- 
|tois begun. 
toic outgrowth. 
Anal membrane | 
and allantoic me- | 
| 
| Entodermal allan- | 
|soderm ventral. 
Projecting ento- | 
| dermal allantoic di- 
| verticulum. 
| Entodermal_ allan- | 
|toic diverticulum. | 
| Allantoic stalk near | 
| cloacal region very | 
| narrow. 
Allantoicstalknear 
| cloaca very narrow. 
