14 
Normentafeln zur Entwicklungsgeschichte der Wirbelthiere. 
Desig- | 
nation 
Measure 
Body Form 
Primitive Streak 
MEN:0en 
ı No. 650 
Trans. 
| No. 624 
| Trans. 
No. 571 
Trans. 
No. 573 
Sag. 
No. 621 
Trans. 
No. 146 
Trans. 
| No. 148 
Front. 
|to tail end 
3.4 mm 
from head 
end to 
caudalend 
3.8 mm 
3.4 mm 
32 
Embryo is flat: practically level with extra-embryonic disk. 
Anterior end of medullary plate raised above adjoining ecto- 
derm. . 
Essentially the same as in No. 650. Anterior end of medullary 
plate is a little more elevated. 
Cephalic end raised above level of surrounding extra-embryonic 
disk; also dips ventrad a little. The back is flat. 
Essentially the same as in No. 571. 
The back is flat. The head bends ventrad a little, 
The back is flat. The head bends ventrad. The pericardial 
chamber projects a little. 
Essentially like No. 619, Table 6. 
The back caudad of the heart is nearly flat. The head and 
heart regions bend ventrad at an obtuse angle. The heart 
projects. 
Head bend right-angled. Body, caudad of heart, bent to a right 
angle. Caudal end of body twisted over to the right. 
Head bend slightly acute-angled. Trunk twice bent approximately 
to a right angle. Caudal end of body rolled over to right. Limb 
buds just visible. 
Head bend nearly right-angled. Neck bend present. Caudal end 
of body spirally twisted to the right. Heart chamber prominent. 
Limb buds project a little. 
Head bend nearly right-angled. Neck bend obtuse-angled. 
Caudal end of body twisted over to right. Brow projects 
beyond heart chamber, which is prominent. A small interval 
separates brow from caudal end of body. 
Head bend acute-angled. Neck bend obtuse-angled. Caudal end 
of body turned over to right. Only a small interval separates 
brow from region of hind limb buds. A slight prominence in 
region of mid-brain. Heart chamber prominent. 
Head bend acute-angled. Neck bend obtuse-angled. Caudal 
end of body bent over to right. Brow projects beyond heart 
chamber, to which the former is near. 
Includes 59 sections of 6 u thickness. Ectoderm and mesoderm 
joined together. Small medullary plate but no medullary groove 
over anterior end of primitive streak. No primitive groove except 
possibly at posterior end. 
Includes 39 sections of Io u. Small medullary plate but no me- 
dullary groove over anterior end of primitive streak. No primitive 
groove. 
Includes 23 sections of 10 u. Medullary groove practically absent 
at anterior end of primitive streak. 
Includes 34 sections of 6 u. anterior to region of anal membrane. 
Very shallow medullary groove over anterior end of primitive 
streak. 
Includes 28 sections of 6 x anterior to anal membrane. Distinct 
medullary groove over anterior end of primitive streak remnant. 
Includes 33 sections of 6 u anterior to anal membrane. Medullary 
tube nearly but not quite closed dorsally over anterior end of 
primitive streak remnant. 
Closely similar to No. 619. Includes 20 sections of 8 u. Anterior 
end of remnant of primitive streak now dorsal to hind-gut. 
Includes 18 sections of 8 u. Medullary tube closed and separated 
from external ectoderm over anterior end of primitive streak 
remnant. Hind-gut is formed ventral to latter point. 
Still a trace left of primitive streak. Includes about 9 sections of 
Io u. Posterior end of remnant of primitive streak joined to hind- 
gut as well as medullary tube. 
Still a slight trace left of primitive streak in caudal end of body. 
Mesoderm in median line is joined to medullary tube and to lateral 
mesoderm. 
In caudal end of body, the median mesoderm is joined to medullary 
tube, to lateral mesoderm and to hind-gut, through a few sections. 
Here no distinct notochord. Cf. notochord. 
