The Prophase in the Ovigenesis and the Spermatogenesis of Planaria etc. 447 
1907. Popoff, M. Eibildung bei Paludina vivipara etc. Arch. mikr. Anat. 
Bd. 70. 
1908. Arnold, G. Spermatogenesis of Ilydrophilus piceus. Arch. f. Zellforsch. 
Bd. 2. 
1908. Goldschmidt, R. Über das Verhalten des Chromatins bei der Eireifung 
und Befruchtung des Dicrocoelium lanceatuin. Arch. f. Zellforschung. 
Bd. I. 
1908. Kühn, A. Die Entwicklung der Keimzellen in den parthenogenetischen 
Generationen der Cladoceren. Arch. f. Zellforsch. Bd. I. 
Description of Plates. 
All the drawings were made direct, using a Zeiss 2 mm. Apochromat, 
with Compens-oculars 8 and 18, and again enlarged. All the drawings, except 
figs. 10, 13 & 16, are made from preparations staiued with the triple-stain de- 
scribed at the beginning of this paper. 
Figs. 10, 13 & 16, are from preparations stained with Thionin & Orange G. 
Figs. 1 — 22 Ovigenesis. Figs. 23— 53 Spermatogenesis. 
Ovigenesis. 
Plate XXII. 
Fig. 1. Resting stage. 
Figs. 2—5. Leptotene stage. 
Figs. 6 — 7. Zytogene stage, commencement of synapsis. 
Ftg. 8. Zytogene stage, synapsis. 
Fig. 8a. Portion of segment of spireme, longitudinal split just connnencing. 
Fig. '8 b. Do. split complete. 
Figs. 9 & 10. Opening out of synapsis, commencement of pachytene stage. 
Figs. 11 — 14. Pachytene stage. Fig. 11, Commencement of the conden- 
sation of the chromatin towards the middle of the linin segments. 
Figs. 15 & 16. Strepsitene stage. 
Plate XXIII. 
Fig. 17. Resting stage. 
Figs. 18—21. Leptotene stage. 
Fig. 22. Commencement of zygotene stage. 
Spermatogenesis. 
Fig. 23. Resting stage. 
Figs. 24—27. Leptotene stage, figs. 27 & 28, cytoplasm left out. 
Figs. 28—31. Zygotene stage. Figs. 30 & 31, synapsis. 
Fig. 32. Late prophase, spindle figure just forming. 
Fig. 33. Late prophase (strepsitene stage . 
Fig. 34a. Polar view of geiuini on the equatorial plane. 
Fig. 34 b. Mode of attacliment of the gemini to the spindle fibres. 
Fig. 35. Telophase of the Ist. maturation division. 
Figs. 36-38. Resting stage of 2nd. maturation division. Spermatocytes II 
order. 
Archiv f. Zellforschung. III. 
30 
