Article révisé par les pairs
| Résumé : | 1. Using the method of Lehmann and some other more accurate cytological methods, the author did not find the autonomous marginal plasma in the unsegmented ovum of the Axolotl. The marginal zone of the unsegmented ovum constitutes an integral part of the animal segment and it is in direct contact with the upper layer of the large granules of yolk which forms the vegetative segment. 2. The crescent of Born appearing in the ovum which is fixed in an oblique position, is not marked by the descent of the marginal plasma, but by the adherence of a small layer of yolk along the superficial cap (the result confirms an observation of Born). 3. The experimental analysis shows the area where the first lip of the blastopore appears at the border of the yolk and it is dependent on a permanent structure. The area is neither affected by the moving plasma nor by the displacement of material which moves under the influence of gravitation. 4. The experimental results show the existence of such a structure as described above and it is situated in all probability in the outer surface. © 1946 S. Karger AG, Basel. |
