No. 2.] THE DEVELOPMENT OF THE NEWT. 287 



" Mir scheint er einzig und allein mit der Bildung der Dotter- 

 substanz in Beziehimg und eine eigenthiimliche locale Ansamm- 

 lung von Nahrstoffen darzustellen." Hertwig suggests the 

 name " Dotterconcrement " as preferable to that of Dotterkern, 

 and justly criticises the term Dotterkern as applied to the body 

 observed in the amphibian egg. I have, however, retained the 

 name yolk-nucleus because of the wide currency that this 

 name has already obtained, and because the designation 

 " yolk-concrement " is open to the construction that this body 

 is a mere concretion of yolk. 



Sabatier ('83) describes the origin and fate of the yolk-nucleus 

 as he observed it in the Arachnids : " ne dans le voisinage 

 immediat de la vesicule germinative, il s'en eloigne progressive- 

 ment. ... II devient plus granuleux et se desagrege 

 progressivement. Ses elements divises en petits globules in- 

 dependante sont en partie resorbes par le vitellus, ou s'intro- 

 duisent en partie entre les grosses spheres vitellines et viennent 

 sourdre a la surface de I'oeuf pour se meler au protoplasme 

 granuleux superficiel." From these observations he draws the 

 remarkable conclusion that the " noyau vitellin " is to be re- 

 garded "comme un element de polarite male, qui se detruit 

 comme tel pour accentuer et completer la sexualite de la cellule 



femelle." 



Will (-84) advances a rather improbable view of the origin 

 of these bodies in the amphibian and insect ova and appears 

 to regard the phenomena in these two groups as practically 

 identical. According to his observations some of the nucleoli 

 in the germinal vesicle of the amphibian egg reach a com- 

 paratively large size, but do not differ from the others in 

 their behavior to staining fluids or other reagents. One or 

 more of these enlarged nucleoli pass out into the body of the 

 egg and there as "yolk-nuclei" take part in the formation of 

 the yolk. Will finds some cases in which the nucleoli change 

 into epithelial cells, but, since in the long run these share in 

 the formation of the yolk the "Endproduct" is the same. 



Stuhlmann ('86) describes the origin of the Dotterkern in 

 the arthropod egg and seems to regard it as originating inde- 

 pendently in the cytoplasm. "Niemals aber konnte ich eine 



