DEVELOPMENT OF PARAVORTEX GEMELLIPARA 479 



Rolle im Stoffwechsel spielt, unci die Entwickelung unci das Wachstum 

 entweder das ganzen Eis oder eines bestimmten Elastomers begiinstig. 



From the foregoing review it is evident, first, that several 

 different cell structures have been designated as yolk-nuclei, 

 and second, that diverse views have been held as to the origin, 

 function, if any, and the fate of the 'Dotterkern,' In the major- 

 ity of instances where the latter was traced its disappearance 

 as a concrete cell organ occurred in the oocyte, A part of the 

 yolk-nucleus observed by Balbiani in Tegenaria, however, re- 

 tained its individuality throughout cleavage and finally became 

 located among the yolk-spheres in the abdomen of the young 

 spider. 



Since Lepechkine's work of 1900 a vast amount of literature 

 has appeared dealing with mitochondria. It is apparently 

 to this class of elements that the true yolk-nuclei described 

 by him and earlier workers belong. Therefore it seems justifiable 

 to replace the name yolk-nucleus with one which is more descrip- 

 tive of its true nature. We propose to use in this paper the term 

 'mitochondrial mass.' 



The cytoplasm or ooplasm of the oogonia is, in well preserved 

 preparations, so finely granular that it resembles an opaque 

 fluid. With the iron-haematoxylin method a light bluish-gray 

 color is characteristic. If the sections be washed too long 

 in the iron alum after their removal from the stain, and sub- 

 sequently counter stained with orange G, the latter imparts 

 to the cytoplasm of the oogonia and oocytes a yellowish brown 

 tint. In such mounts the mitochondrial mass, which also takes 

 the orange stain, is detected with difficulty. Those prepara- 

 tions, however, which retain a sufficient amount of the blue 

 haematoxylin show the mass even in its earliest stages. Figure 

 6 was drawn from such an ovary. A small group of brownish 

 granules in the third oocyte which shows a membrane on the 

 right hand side of the ovary is the first indication of the mito- 

 chonch'ial mass. A study of the nuclei in the yoimger cells 

 does not lead to the conclusion that the granules are of nuclear 

 origin. They are rather to be regarded as bodies which have 

 arisen in the cytoplasm under the influence of nuclear energy. 



