131 
between the other forms as regards the closure of the 
blastopore. The results of my experiments for Rana fusca 
ave been combined in a single figure, composed from 
many other figures, two drawings being each time super- 
posed and held up to the light, the details of one figure 
being soi ag way transferred to the other. 
The eggs seat at the animal pole teach us what 
follows ae fig. 3 
he dorsal Blaanierie lip is formed very little below 
the equator (much less than 25° or 30°, see above) and 
a 
€ 
Fig. 35. Results of pricking experiments on the frog egg (Rana fusca). 
a eight-celled stage seen from the side, b stage with me- 
els eid plate. 
‚C,d,‚e, situation of the ate at the points of intersection 
of the first three cleavage furr 
‚3, 4, anterior border of the ‘blastopore in successive 
gills, 
* (fig. a) limit of black ‘and white area, 
* (fig. b) edge of the so-called sense-plate. 
immediately begins to grow over towards the vegetative side. 
The ventral blastopore lip is formed about diametrically 
opposite the animal pole, slightly more to the dorsal side. 
This border practically does not move, so that the closing 
of the blastopore finally takes place at this same point. 
From this it follows that the dorsal blastopore lip progresses 
through a little less than 90° (estimated not under 
When the blastopore has finally narrowed to a short slit 
and the medullary folds arise, this slit consequently still lies 
almost diametrically opposite the animal pole which is situat- 
ed exactly in front of the cerebral plate. The distance 
