p 



The Nebenkern in the spermatogenesis of Pulmonata. — Helix and Arion. 439 



Explanation of the Figures. 



All figures were drawn with the camera with the paper on the 

 work-table. The protoplasm could only be partly so traced but in 

 everj^ case the coarseness of the reticulum was obtained in this way. 



Plate 32. 



Figs. 1 — 20. Helix pomatia. Tigs. 21 — 25. Arion. Figs. 1, 1 a, 

 10 a, 12, 13, 21 — 25 are from Professor Hermann's preparations. 



Figs. 1 — 15. Spermatocytes of first order. Helix pomatia. 



Fig. 1. Resting spermatocyte. Hermann's mixture pyroligneous 

 acid. X 2250. 



Fig. 1 a. Same cell optical section. 



Fig. 2. Resting spermatocyte. Folded attractionsphere. Hermann's 

 mixture pyroligneous acid, iron-alum haematoxylin. X 2250. 



Fig. 3. Attractionsphere diifusely stained, centrosomes and i-adiation, 

 chromosomes already rings. Perenyi's mixture Bordeaux red. iron-alum 

 haematoxylin. X HOO. 



Fig. 4. Similar preparation, sphere indented, same fixation and 

 stain. X comp, ocular 6, apoch. 1.5 mm, projected on work-table. 



Fig. 5. Similar preparation, nucleus more advanced , radiation 

 stronger. Sublimate acetic, same stain. 



Fig. 6. Resting spermatocyte. Sublimate acetic, iron-alum haemato- 

 xylin. X 2250. 



Fig. 7. Early prophase, centrosomes approach nuclear membrane. 

 Perenyi's mixture , Bordeaux red, iron - alum haematoxylin. X 2250. 



Fig. 8. Prophase later, vide text. Same fixation and stain. X 2250. 



Fig. 9. Still later prophase, vide text. Same fixation and stain. 

 X 2250. 



Fig. 10. Pole of amphiaster, large centrosome, vide text. Same 

 fixation and stain. X 2250. 



Fig. 10 a. Pole of nearly comple amphiaster from below. Sphere 

 fragments in surface view. Hermann's mixture pyroligneous acid. X 2250. 



Fig. 11. Amphiaster centrosomes as in Fig. 9, vide text. Perenyi's 

 mixture, Bordeaux red, iron-alum haematoxylin. X 2250. 



Fig. 12. Prophase. Hermann's mixture pyroligneous acid. X 2250. 



