150 
canal, as described by SCOTT and OSBORNE, was never 
observed by her. SCHANZ (1887) in Triton punctatus comes 
to the conclusion that the blastopore is constricted in 
the middle, the anterior opening becoming the neuren- 
teric canal, the posterior opening the anus. HOUSSAY 
and BATAILLON (1880) on the contrary find in the 
axolotl: “qu'il n'y a pas de canal neurentérique, que le 
blastopore demeure toujours ouvert et qu'il devient anus 
définitif”. Next comes the accurate investigation of MORGAN 
(1889, 1890) for the axolotl. He too finds that the hindmost 
part of the blastopore passes into the anus, the anterior 
part being enclosed between the medullary folds. Since my 
conclusions are closely akin to those of MORGAN, | shall 
revert to them in detail presently. 
GOETTE (1890) similarly sees in some Urodelans (7 riton, 
Siredon) the rear end of the blastopore pass into the anus. 
A few further observations of recent times as to the fate of 
the blastopore may be touched on : those of DE LANGE (1907, 
1912) and ISHIKAWA (1908) concerning Megalobatrachus 
maximus, of KUNITOMO (1911) concerning Hynobius and 
of SMITH (1912) concerning Cryptobranchus alleghaniensis. 
All agree that the hind part of the slit-like blastopore 
remains open as the anus, the anterior part being overgrown 
by the medullary folds, except ISHIKAWA who considers 
this course of events as an exception only, the anus as 
a rule springing up as an independent formation, which is 
denied by DE LANGE (1912). 
For Petromyzon and Dipnoans most investigators hold that 
either the whole blastopore or its hind end passes into the anus. 
Amblystoma tigrinum. — My own investigations concerning 
the axolotl all go to confirm the conclusions reached by 
most of my predecessors, viz: that the rear part of the 
blastopore passes into the anus. If then | give a brief 
survey of my observations, it is with the express object 
of emphasizing some few circumstances which were not 
noticed by former investigators and seem to me of importance 
in giving a correct interpretation. d 
e stage represented in fig. 4l a (text) and fig. 6 
(plate III) corresponds absolutely with that of fig. 40 aand 
fig. 1 (plate II) for Rana esculenta. Here also the medullary 
folds begin to appear and the blastopore has contracted 
to a short longitudinal slit. Already in fig. 6 (plate) it IS 
evident how much more the dorsal side is developed than 
