152 
the ectoderm (a) where the future anus might be expected, 
it a similar state of affairs were to take place as in Anuians. 
Immediately behind that shallow depression we find here 
the same thickening of the ectoderm (*) as noted in Rana 
(cf figs. 1, 2, 3, plate II). Thus there is no fundamental 
difference, on the contrary agreement in every respect with 
what we found in Rana. 
New in Rana we stated that the blastopore, after becoming 
slit-like, continues to move backwards a small distance, 
approaching the future anus, which manifests itself in 
longitudinal sections in that the small lip which represents 
the ventral blastopore border becomes a little shorter. 
This now we see happening also in somewhat further 
advanced stages of the axolotl-egg: in sections the ventral 
lip gets shorter and soon, being here already small, it 
disappears altogether. In the egg shown in fig. 41 b ande 
(text) the medullary folds are on the point of fusing, except 
at the fore and the rear end. The blastopore still appears 
as a slit. The longitudinal section (fig. 7) shows that the 
ventral blastopore lip has nearly disappeared: as a result 
of the backward movement the rear end of the slit-like 
blastopore has arrived at the spot where the anus must 
break through! 
Particularly interesting is next the egg shown in fig. 41 
d, where the medullary tube has just closed except at the 
hindmost extremity where the anterior part of the slit-like 
blastopore has just been overgrown by the medullary 
folds. Whilst in Rana the whole blastopore is in thís way 
enclosed, in the axolotl the medullary folds leave an 
opening over the rear end of the blastopore, which íS 
the anus (a). 
Only one egg in this stage was found by me amongst 
my material. This was cut into longitudinal sections. 
MORGAN studied a similar egg in transverse sections. 1 repro- 
duce here the outline of his excellent figures which confirm 
my views in every way. Fig. 42 a represents a section 
through the medullary tube just in front of the blastopore. 
Under it the anal diverticulum has been intersected. The 
medullay folds just meet. Figs. 42 b and c show the 
blastopore in its anterior half as is of course the case in many 
succeeding sections The medullary folds meet over the blasto- 
pore the latter itself constituting the neurenteric canal. Figs 
42 d and e are still further back, the medullary folds aré 
