4/O NOTES. 



forms but a part of the permanent intestine, and the primitive 

 mouth (at least in the higher animals) does not become the 

 permanent mouth. 



G5 (i. 196). Primitive germ-layers (UastopJiylla) . As the 

 two primary germ-layers (entoderma and exoderma) originally 

 form the sole histogenetic rudiment of the whole body, and as 

 the mesoderma, the nutritive yelk, and all other accessory parts 

 of the germ have developed only secondarily from the former, 

 1 consider it very important to distinguish between the primary 

 and secondary germ-layers. The latter, to distinguish them 

 from the former, might be called " after germ-layers " (bias- 

 telasma). 



66 (i. 201). Unequal Cleavage and Hood-gastrula (Seg- 

 mentatio incequalis et Ampliigastrula). Next to Amphibia the 

 most accessible examples for observation of unequal cleavage 

 and the Amphigastrula are afforded by the indigenous Soft- 

 bodied Animals (Mollusca) and Worms (Snails and Mussels, 

 Earth Worms and Leeches). 



67 (i. 202). The Colour of Amphibian-eggs is occasioned by 

 the accumulation of dark colouring-matter at the animal pole of 

 the egg. In consequence of this the animal-cells of the exoderm 

 appear darker than the vegetative cells of the entoderm. In 

 most animals the reverse is the case; the protoplasm of the 

 entoderm cells being usually darker and more coarsely granulated 

 (vol. i. p. 197). 



68 (i. 207). Hood-gastrula of Amphibia. Cf. Robert Remak, 

 ' On the Evolution of Batrachia " (" Ueber die Entwickelnng der 

 Batrachier," p. 126 ; Plate XII. Figs. 3-7). Strieker's " Manual 

 of Tissues" ("Handbuch der Gewebelehre," vol. ii. p. 1195- 

 1202 ; Figs. 399-402). Goette, " History of the Evolution of 

 Boinbinator" (" Entwickelungsgeschichte der Unke," p. 145; 

 Plate II. Figs. 32-35). 



69 (i. 214). Hood-gastrula of Mammals. Eduard van 

 Beneden, " La maturation de 1'oeuf, la fecondation et les premieres 

 phases du developpement embryonnaire des Mammiferes, d'apres 

 des recherches faites chez le lapin." Brussels, 1875. No figures 



