DOI 
Amphibia, however, but also in Teleostei, where the earliest 
development differs in so many respects from that of the Amphibia, 
it may be taken for granted that the animal pole afterwards 
exactly indicates the anterior end of the embryo. When in 1913 | 
tried to show that in the anchovy the cerebral plate occupies 
nearly the same place as the animal pole, I overlooked a paper in 
which Sumner (1904) describes pricking experiments on teleostean 
eggs, particularly those of some North-American species of Fundulus. 
When he pricked in the centre of the still small germinal 
dise which later extends concentrically over the whole egg, this 
mark was also found back exactly in front of the foremost point of 
the rudiment of the embryo. This points to a general prevalence of 
such a relation between the animal pole and the cerebral plate 
in Craniota. Nevertheless it should be mentioned here that HELEN 
Dean Kina (1902) in Bufo and Eycresnymer (1902) in Necturus 
concluded from similar pricking experiments that in these the animal 
pole is found some distance in front of the transverse head-fold 
and that the latter even lies halfway between animal pole and egg 
equator. However it seems to me that these last experiments are 
not so conclusive that they would preclude the possibility that on 
closer examination these forms also might turn out to conform to 
the rule. Further investigations on this point are wanted. 
Besides the animal pole | marked in the 8-celled stage other 
crossing points of cleavage lines, especially the four intersections of 
the equatorial cleavage groove, which, as appears from fig. 1, lies 
at a considerable distance above the equator of the egg, and the two 
meridional grooves. We shall indicate these points by 6, c and d, 
4 lying on the side where the white area of the lower portion of 
the ege reaches farthest upwards and which must be denoted as 
the dorsal side. On the opposite ventral side c will lie, ¢ denoting 
the two lateral crossing points. I did not sueceed in marking also 
the vegetative pole without being troubled at once by a considerable 
extraovate. Hach egg always had only one single mark. Although on 
some eggs marks were made in two or even three of the just- 
mentioned spots [ am sorry I could pursue none of these eggs as far 
as the appearance of the medullary plate without all the marks, or 
all except one, coming off. Such eggs were always chosen which 
in the eight-celled stage presented the most regular appearance, 
without large “cross-lines” (‘‘Brechungsfurchen’’) in the points of inter- 
section and in which the highest point of the white area was exactly 
cut by one of the two meridional cleavage planes, so that it 
might be assumed that the first cleavage plane coincided with the 
