SIGNIFICANCE OF KUPFFER’s VESICLE. 
11 
Sedgwick’s idea that the present anus is the same structure, 
nor do I aceept the proof brought forward by Miss Johnson 
on the point as far as regards the newt. The blastopore is 
indeed the primitive anus, hut it does not coincide with the 
actual anus ; the primitive anus was closed by the same process 
as that which removed the hollow neurochord from the surface of 
the body, and is represented by the neurenteric canal, which, 
in spite of Miss Johnson’s failure to find it in the newt, is, I 
believe, never altogether unrepresented in A r ertebrate embryos. 
Miss Johnson’s researches on the primitive groove in the newt 
are extremely valuable as proving that there is originally a 
fusion of the three layers along the whole line of the primitive 
elongated blastopore. 
The notochord was discovered long ago to originate in 
many Vertebrates in close relation to the hypoblast, and it was 
immediately concluded by morphologists that the notochord 
was evolved from the wall of the intestine. Some have 
pointed to the typhlosole in the earth-worm as the homologue 
of the notochord ; notwithstanding that the typhlosole is a 
pushing in and the notochord a growth outwards. The typh- 
losole is represented beyond a doubt by the spiral valve in 
Elasmobranchs and other fishes, and has never given rise to 
anything outside of the intestine. Now, the notochord in the 
course of evolution never could have arisen from the intestine, 
for this reason : the dorsal aorta of Vertebrates is homologous 
with the subintestinal vein of an Annelid, the blood in both 
flows the same way, and the two have the same relations to the 
intestine. Therefore, if the notochord had been evolved from 
the wall of the intestine the aorta would in the Vertebrate have 
been on the dorsal side of the notochord, not, as it actually is, 
on its ventral side. A glance at fig. 2 of the Plate illustrating 
this paper will show that one might as easily suppose that in 
the herring the notochord was developed from the neurochord 
as from the hypoblast. I am not going to sustain that the 
neurochord gave origin to the notochord, because I think it 
unlikely that a nervous structure would have given rise to a 
skeletal one. I believe the notochord to be really mesoblastic, 
