NOTES. 469 



mentella, or cleavage-cells, which, constitute the Morula at the 

 close of palingenetic egg-cleavage, generally appear entirely 

 similar, with morphological difference in size, form, or con- 

 stitution. This does not, however, hinder the fact that these 

 cells have separated, even during cleavage, into animal and 

 regetable cells, have differentiated physiologically, as is indicated 

 in Figs. 2 and 3, Plate II., as probable. 



61 (i. 189). The Bladder-germ of Archiblastic Animals 

 (blastula, or blasto splicer a), which is now commonly known as 

 the germ-vesicle, or, more accurately, as the " germ-membrane 

 vesicle," must not be confused with the essentially different 

 " germ- vesicle " of amphiblastic mammals, which is better called 

 the " intestinal-germ vesicle" (g astro cystis). The gastrocystis 

 and the blastula are still often united under the name of " germ- 

 vesicle, or vesicula blastodermica" Cf. vol. i. p. 290. 



62 (i. 192). The Definition of the Gastrula was first 

 established by me in 1872, in my "Monograph of Chalk-sponges " 

 (vol. i. pp. 333, 345, 466). There I already gave due weight to 

 the u extremely great significance of the gastrula in reference 

 to the general Phylogeny of the animal kingdom" (p. 333). 

 " The fact that these larval forms re-occur in the most different 

 animals, cannot, I think, be sufficiently estimated, and bears 

 plain witness to the former common descent of all from the 

 Gastraea " (p. 345). 



63 (i. 194). The Uniaxial Outline of the Gastrula is, on 

 account of the two different poles of the axis, more accurately 

 described as a diplopolic uniaxial form (a sternometric outline : 

 conoid-form, or cone). Cf. my " Promorphology " (" Generelle 

 Morphologie," vol. i. p. 426). 



64 (i. 194). Primitive Intestine and Primitive Mouth. My 

 distinction of the primitive intestine - and primitive mouth 

 (protogaster and protostoma) from the later, permanent intestine 

 and mouth (metagaster and metastoma) has been variously 

 attacked ; it is, however, as much justified as the distinction of 

 the primitive kidney from the. permanent kidney, of the primitive 

 vertebrae from the permanent vertebrae. The primitive intestine 



