440 ELMER L. SHAFFER. 



into the cytoplasm" (page 508). More recently, Nakahara 

 ('18) has described in the oocytes of Perla a deeply staining 

 mass of granules in the cytoplasm closely surrounding the nuclear 

 membrane, which he calls the "yolk-nucleus." This later breaks 

 away from the nuclear membrane, becomes insignificant and 

 finally disappears. Nakahara is of the opinion that the nucleoli 

 of the oocyte nucleus are derived from the passage of material 

 from the "yolk-nucleus" into the oocyte nucleus, and hence 

 nucleoli are extra-nuclear in origin. These interpretations of 

 Nakahara are hardly excusable since at this late date he has 

 had the advantage of a large mass of data bearing on mitochon- 

 dria, and it is evident that he has not made a proper study of 

 the literature. Many similar cases of almost riotous interpreta- 

 tions of mitochondrial structures might be mentioned, many of 

 them inexcusable in light of the recent studies on the mitochon- 

 dria. As has been before stated, many of these erroneous inter- 

 pretations are based upon material prepared without regard for 

 the special technical processes involved for the demonstration of 

 mitochondrial structures. Perhaps the best example of this is 

 the work of Giardina ('04). This writer has studied the oocytes 

 of a number of insects (Mantis, Periplaneta, Stenobothrus, Gryllus] 

 and the gastropod, Helix arvensis. In all of these forms, Giardina 

 has described a special zone of the cytoplasm immediately sur- 

 rounding the nucleus to which he assigns the name "zona 

 plasmatica perinucleare." At times this zone may appear 

 granular, striated, vacuolated, homogeneous, etc., and is always 

 sharply delimited from the rest of the cytoplasm by a membrane. 

 After considerable discussion as to its physical state, Giardina 

 comes to the conclusion that it is a formation in situ of the cyto- 

 plasm under the action of substances from the nucleus, and that 

 it acts as an intermediary between the nucleus and the cytoplasm 

 in the nutrition of the egg. From a study of Giardina's figures 

 and a comparison with the oocytes of Cicada fixed in Bouin's 

 fluid for varying lengths of time (Figs. 39, 41, 42), it becomes at 

 once evident that the "zona plasmatica perinucleare" of Giardina 

 is nothing more than poorly-fixed mitochondria arranged in a 

 perinuclear zone. Duesberg ('12) is of this opinion as is also 

 Faure-Fremiet ('10). 



