THE GERM-CELLS OF CICADA (lIBICEN) SEPTEMDECIM. 44! 



It thus seems that perhaps it is quite general in the insects 

 that the mitochondria of the oocyte are first arranged in a 

 definite zone around the nucleus during the period in which 

 they increase in numbers, and in the older oocytes the perinuclear 

 zone of mitochondria becomes dispersed towards the periphery 

 of the oocyte and becomes concerned in the process of yolk- 

 formation. 



4. Significance of the Perinuclear Zone of Mitochondria. 



(a] Relation to Yolk-nuclei. As I have before indicated, the 

 occurrence of a perinuclear zone of mitochondria is quite com- 

 monly met with especially in the female germ-cells during the 

 growth period. I shall not attempt a lengthy review of the 

 literature in this regard since we already have the excellent 

 review of Duesberg ('12), but I wish to point out some of the 

 significant facts which have a bearing on the problems presented 

 here. I wish merely to discuss the origin and homologies of 

 the yolk-nucleus or "corps de Balbiani," mention of which has 

 been made in almost every work in oogenesis which has appeared 

 in the past two decades. As has been shown in Duesberg's 

 ('12) review, much of the recent work in this connection has 

 demonstrated that these bodies (yolk-nuclei) are in many cases 

 partly constituted of mitochondrial substance. O. Vander 

 Stricht ('04) has shown that the "couche vitellogene" surround- 

 ing the nucleus of the oocyte of the bat is of a mitochondrial 

 nature, and von Winiwarter and Sainmont ('09) have described 

 a zone of granular mitochondria around the nucleus of the 

 oocyte in the kitten, which they homologize with the yolk- 

 nucleus and "couche vitellogene" of Vander Stricht. Recently, 

 Gajewska ('19) has shown that in Triton the yolk-nucleus is made 

 up of three substances: "Zuerst eine Anhaufung von Ergasto- 

 plasmatischer Substanz (Ergastoplasma-Dotterkern), dann ein 

 Mitochondrienkonglomerat (Dotterkern als Kornerkonglomerat) 

 und endlich ein Haufen von Fettkugeln und Eiweissplattchen. 

 Die Muttersubstanz fur den Dotterkern ist der perinukleare 

 Ring (couche vitellogene)" (p. 116). 



The fact which I wish to emphasize here is that in all cases the 

 yolk-nucleus has its beginning in the young oocyte in the form 



