FATE OF BLASTOPORE, ETC., IX CHELOXIA g 9 



f is four sections behind e. The enclosure his gone one step 

 further. 



g is two sections behind/. The enclosure is now complete, 

 but the epiblast is still continuous witli the epiblast of the 

 extra- embryonic blastoderm. The epiblast is tliick at 

 this point of reflection. 



h is two sections behind (j. The enterou has now united 

 with the allantoic cavity. 



i is two sections behind li. The connection of tlie epiblast at 

 the ventral median line is now cut and the tail lies 

 entirely free in the amniotic cavity. 



i is seven sections behind /. It is in the reoiou of tlie cloacii. 

 The AVolffian ducts empty into the cloaca in this and 

 next section. 



k is nex't to/. The ventral median i)art of the tail is given 

 (^n a, hu-ger scale in Ser. XIV //. on the s;une ])l;ite. The 

 three layers are distinctly separate. 



I is eight sections behind /.-. The ventral median part of the 

 tail is ag.iin given on a larger scale in Ser. XW I' on the 

 same plate. Here the wall of the enteron is distinctly 

 united with the epiblast, :ind there can not be much doubt 

 tliMt this is the proctoda'uui. Note how the tw<j cell-layers 

 of the epiblast behave in this section. The section in 

 front of, and the two sections beliind, I .-u'e like /, and the 

 proctodeum extends thus over four sections, but for s(mie 

 five sections further forwards the ej)ibl:ist shows some 

 tliickening in the ventral median line which is the 

 greater, the nearer to the proctodieum, 1 »ehind, t he connec- 

 tion of the epiblast with the enteric wall is loo-iened at the 

 third section behind /. 



m is six sections behind /. The enteroii is contracted very 

 much immediately after the level of the proctodeum. In 

 tliis, only the upper part has a lumen. 



n is two sections behind in. The enteron is now reduced to 



