434 ELMER L. SHAFFER. 



chondria is still found at one pole of the nucleus, they gradually 

 completely encircle the nucleus. After this period, when the 

 synaptic threads have become diffuse and the "germinal vesicle" 

 is established, the mitochondria increase greatly in numbers 

 and are found localized in a zone immediately surrounding the 

 nucleus (text-fig. 3, and Figs. 83, 84). 



This perinuclear zone of mitochondria is sharply delimited 

 from the rest of the cytoplasm. Faure-Fremiet ('08) has de- 

 scribed the mitochondria of the oocytes of Julus as being similarly 

 arranged in a perinuclear zone whose cytoplasmic limit is defi- 

 nitely marked by the presence of a membrane formation. I can 

 find no evidence for the presence of such a limiting membrane in 

 Cicada. The mitochondria continue to increase greatly in 

 numbers in the perinuclear region up until the stage in which 

 the cytoplasmic volume of the oocyte is greatest (Fig. 85). 

 Throughout the period in which mitochondria are forming in the 

 perinuclear zone, the nuclear membrane remains intact at all 

 times as is evidenced in material improperly fixed in which the 

 nuclear membrane has shrunken away from the cytoplasm as 

 shown in Fig. 85. Neither is there any evidence that any nuclear 

 materials are discharged or extruded into the cytoplasm at any 

 time. There are many descriptions in the literature of bodies 

 in the cytoplasm of oocytes which have been derived from the 

 discharge of nuclear materials. Goldschmidt and his pupils have 

 maintained that the mitochondria are derived from the passage 

 of nuclear materials into the cytoplasm, but there is no evidence 

 that this is the case in Cicada. Vejdovsky ('12) has described 

 in the oocytes of Aphrophora large deeply staining globules and 

 vacuoles (compare my Fig. 42). He does not relate these struc- 

 tures to the mitochondria in any way, but indicates that these 

 nucleolar-like bodies in the cytoplasm are derived by a "nucleoli- 

 zation" of the chromosomes and a casting-out of the resulting 

 nucleoli into the cytoplasm. He is of the opinion that the 

 vacuoles represent the escaped nuclear sap, there being no nuclear 

 membrane present at this time. In the first place, it seems very 

 doubtful that the nuclear membrane does disappear at any time 

 in the resting nucleus. Secondly, if there is a nuclear membrane 

 present it is difficult to see how such solid bodies as nucleoli 



