474 EYCLESH YMER. [Vor. XIV. 
much smaller (Fig. 91), and the distance between the dorsal lip 
and the exovate further reduced. At 2 P.M. the exovate dis- 
appeared entirely (Fig. 92). 
At 5 p.m., April 4, an egg was selected on which a natural 
or accidental mark was found just without one of the extremi- 
ties of the semicircular blastopore. Near this mark a slight 
puncture was made, as shown in Fig. 93. At Io P.M. the 
blastopore had changed to the circular form represented in 
Fig.94. The marks were at this time much nearer the blasto- 
poric margin than in the earlier stage. At 6 a.m. on the fol- 
lowing morning the blastopore had changed to the linear form. 
The exovate was not carried in, but lay just at the edge of 
the blastopore, as shown in Fig. 95. 
After much searching, another egg was found with an acci- 
dental mark at one extremity of the crescentic blastopore, in 
the position shown in Fig. 96. Five to six hours later the 
blastopore had changed to the form shown in Fig. 97. At this 
time the mark had been carried to the very margin of the 
blastopore, as represented in the figure. Six hours later the 
blastopore had become circular in form (Fig. 98), and the mark 
had been carried into the blastopore. 
Summary of Experiments. 
If 
Experiments I, 2, 5-15, 17, 18 indicate that the upper pole 
in Acris represents that portion of the egg which later forms 
the anterior end of the embryo. 
Experiments 46-54 show similar results in Bufo. 
Experiments 59-64 show the same to be true of Amblystoma. 
II. 
Experiments 50-56 indicate that in Bufo an area lying mid- 
way between the upper pole and the point which marks the first 
beginning of the blastopore later forms the mid-dorsal portion 
of the embryo. 
Experiments 65—72 show like results in Amblystoma. 
