The cellnlar elements of the ovary of Platyphylax designatus Walk. 233 



size tlie oöcytes being tlie larger- as yet the nuclei are similar in 

 structure. Youngest group in ovary C. 



Tlie paired cliromosomes of tlie nurse-cells begin to cliange, and, 

 some first becoming tetrads, break up into a number of pieces. Tliese 

 at first remain in small groups and tben become distributed tbrougbout 

 the nucleus. 



In the oöcyte nucleus the paired chromosomes, some first becoming 

 tetradS; disappear as such but at a later stage than in the nurse- 

 cells. They remain within the achromatin mass, former thread, 

 becoming small rods or granules. 



The nucleolus of the nurse-cell nucleus persists; at first it does 

 not stain or is very lightly tinged. In older pupal stages it stains 

 darkly and we then find several in eacli nucleus, their number in- 

 creasing with the age of the cell. 



The nucleolus of the oöcyte also persists. It is always unstained 

 or colored very lightly. In older pupae it fills with vacuoles and 

 finally decreases in size. 



All divisions are mitotic. 



Berlin, im August 1906. 



Bibliography of Platyphylax. 



1. E. Bessels, Studien über die Entwicklung der Sexualdrüsen bei den Lepi- 



dopteren. Diese Zeitschr. Vol. XVII. 1867. 



2. A. Brandt, Über die Eiröhren der Blatta (Periplaneta) orientalis. Mem. 



TAcad. Imp. des Sc. de St. Petersbourg. Vol. XXI. 1874. 



3. Über das Ei und seine Bildungsstätte. Leipzig. 1878. 



4. A. Brauer, Über das Ei von Branchipus Grubii von der Bildung bis zur 



Ablage. Abb. Akad. Wiss. Berlin. 1892. 



5. A. Cerruti, Sülle »risoluzioni necleolari« nella vescicola germinativa degli 



oociti di alcuni vertebrati. Anat. Anz. Vol. XXVI. 1905. 



6. C. Claus, Beobachtungen über die Bildung des Insecteneies. Diese Zeit- 



schrift. Vol. XIV. 1864. 



7. L. J. Dublin, On the nucleoli in the somatic and germ cells of Pedicellina 



americana. Biological Biül. Vol. VIII. 1905. 



8. A. GiARDiNA, Origine del' oocite e delle cellule nutrici nel Dytiscus. 



Internat. Monatsschrift für Anat. und Phys. Vol. XVIII. 1901. 



9. Sui primi stadii dell' oogenesi, e principalmente suUe di sinapsi. Anat. 



Anz. Vol. XXI. 1902. 



10. J. Gross, Ovarien von Mallophagen und Pediculiden. Zool. Jahrb. Anat. 



Vol. XXII. 1905. 



11. Untersuchungen über die Histologie des Insectenovariums. Zool. Jahrb. 



Anat. Vol. XVIII. 1903. 



