No. 3.] BASIS OF THE AMPHIBIAN EMBRYO. 471 
just above the equatorial zone, and in a meridian passing 
through the centre of the crescentic blastopore. Seven eggs 
developed. In three (Figs. 50, 51, 54) the exovates were 
located in or very near the transverse portion of the neural 
fold. In one (Fig. 52) it was far without, and in one (Fig. 53) 
far within. In two eggs (Figs. 55, 56) the exovates at the 
upper pole were detached. 
In those eggs in which the punctures were made at, or 
slightly above, the equatorial zone, the exovates occupied the 
positions shown in Figs. 50-56. In most cases they lay near 
a transverse line marking the middle of the embryo. 
Series III, — Amblystoma punctatum. 
The egg of Amblystoma, owing to its large size and the ease 
with which the membranes are removed, is well suited for 
experimental work. The results of the experiments performed 
are given in greater detail than in the preceding forms. 
Ten eggs in second cleavage were selected at 8 a.m., April 
I, 1895; three were punctured in the inner ends of two of the 
large cells lying on either side of the first cleavage groove, as 
‘shown in Fig. 59. In two of these the exovates were so large 
that abnormal embryos were formed. In one the exovates were 
very minute. At the end of seventy-two hours the neural fold 
appeared. The positions of the exovates, with reference to the 
neural fold and the median plane of the embryo, are shown in 
Fig. 60. 
Three eggs were punctured at the inner ends of the large 
cells lying diagonally opposite, as shown in Fig. 61. In one 
the neural fold was visible at the end of seventy-three hours. 
The positions of the exovates, with reference to neural fold and 
the median plane, are shown in Fig. 62. In one case the 
exovates fused into a common mass, which, however, did not 
entirely obscure the normal relations. At the end of sixty to 
seventy-five hours, the position of the fused mass was far 
within the neural fold and at the left of the median line. 
The remaining egg died soon after puncturing. 
Four eggs were punctured in the ends of the adjacent cells 
on the same side of the first groove, as shown in Fig. 63. In 
