262 K. MITSUKURI. 



obsei'vation whether such a distinction is possible in Mammalia. I am 

 only inclined to think that, since the reptilian and mammalian eggs 

 are alike in so many points, what is tree in the former as regards the 

 development of the alimentary canal will in the main be found true also 

 in the latter. I can also find inChelonia nothing corresponding to 

 his " proto-chordal plate." As to whether there is such an annular zone 

 of hypoblast as he describes which gives rise to the mesoblast I wish to 

 express no opinion. That tlie '' FÎ umpfmesoblast " arises entirelv 

 within the embryonic shield from the materials derived from the 

 primitive knob I hope to have made at least probable in the preceding- 

 pages, but whether some temporary mesoblastic structures of the 

 embryo may not arise in Rep til ia from such an annular zone as he 

 describes, I am not in a position eitlier to stffirm or to denv. 



